For most PVC toilet drains, the Oatey Level-Fit 43503 is the standard pick: it solvent-welds over 3-inch or inside 4-inch PVC pipe, has a plastic ring and is UPC and ASTM D2665 listed. For a 3-inch ABS line, the Oatey 43506 is a black ABS flange that fits inside 3-inch pipe and comes with a test cap. Match the pipe material and how the flange meets the pipe before you buy, then set it on top of the finished floor.
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A familiar brand or nominal size is only the beginning of the order. Confirm the actual connection and complete installation before choosing PVC, ABS or a cast-iron-body flange.
Compare the actual connection, not just the material
| Example | Body and connection | Check before buying |
|---|---|---|
| Oatey 43503 | PVC; over 3-inch or inside 4-inch Schedule 40 DWV pipe | Pipe material, available socket engagement and finished height |
| Oatey 43506 | ABS; inside 3-inch Schedule 40 DWV pipe | Actual bore, approval for inside fit and test-cap instructions |
| Sioux Chief 886-GI | Cast-iron body; gasket connection inside nominal 4-inch DWV pipe | Specified gasket fit, pipe condition and compatible installed layout |
The first two are linked stock examples. The cast-iron model illustrates a separate manufacturer-defined category; it is not a verified Amazon purchase option in this comparison.
Oatey 43503: PVC with a plastic ring
Choose Oatey 43503 for a compatible PVC installation calling for its over-3-inch or inside-4-inch connection. The current maker page (oatey.com) and linked submittal (media.oatey.com) identify that model and its plastic ring.
Skip it if you need a flange that fits inside a 3-inch pipe, over a 4-inch pipe, or connects directly to an incompatible material. The phrase 3 or 4 inch does not make all those arrangements equivalent.
The checked standard new Amazon offer showed stock from Amazon.com. Both model and part fields matched 43503. This is the open model without the molded test cap identified on other models.
Check the delivered part, current instructions and required connection depth. Do not order by color alone, and do not assume the flange includes the seal, closet bolts or floor fasteners needed for the complete installation.
Check Oatey 43503 PVC closet flange on Amazon →
Oatey 43506: ABS with an inside-pipe connection
Choose Oatey 43506 only where its inside-3-inch ABS connection is suitable and accepted for the actual installation. The maker page (oatey.com) identifies it as a testable inside-fit flange.
Skip it as a direct replacement for the connection geometry of 43503. Also skip it when the pipe bore, condition, governing requirements or required drain configuration do not support that inside-fit arrangement.
The current linked submittal distinguishes this model from the broader over-3/inside-4 family. Its footnote excludes Inside Fit from the sheet’s UPC applicability. Have the actual approval requirements resolved rather than relying on a general family badge.
The checked standard new offer showed stock from bestbrandsupply and matching 43506 model and manufacturer-part fields. Confirm the supplied test cap and its current removal/testing instructions. This guide gives no permission to pressure-test a plastic drainage system with compressed air.
Check Oatey 43506 ABS inside-fit flange on Amazon →
Cast-iron flange and cast-iron pipe are different labels
A product described as a replacement for cast-iron pipe may have a plastic body. Read the actual material field instead of interpreting its intended pipe connection as the flange’s composition.
Sioux Chief’s 886-GI page (siouxchief.com) identifies a cast-iron flange body. Its current linked PushTite sheet (cdn.siouxchief.com) distinguishes the cast-iron body from the family’s white and black ABS bodies and shows an inside-pipe gasket connection.
That example is not a traditional flange connection requiring the same joining method as every other cast-iron fitting. The specific gasket arrangement and suitable pipe opening matter. Do not add solvent cement to a gasket connection based on instructions for a plastic socket flange.
For older iron piping, have the bore, sealing surface, pipe support and surrounding material assessed before choosing a repair. A nominal pipe description does not prove that scale, damage or an existing fitting will accept a particular insert.
No exact stock Amazon offer for 886-GI was verified in the checked search. A generic Sioux Chief result proved to be an unrelated floor-drain part and was excluded.
Inside fit, outside fit and spigot need separate measurements
Write down the pipe material and nominal size, then identify the surface the flange must engage. An inside-fit outlet enters the pipe bore. An over-pipe hub fits the specified pipe exterior. A spigot-style connection needs its specified receiving fitting.
Measure the usable opening and available connection length after inspecting the pipe. Do not treat a rough measurement across an old corroded opening as proof of the nominal pipe size.
Inspect the actual drawings when comparing 3-by-4 descriptions. A label may describe alternate fits rather than an unrestricted outlet that suits any existing fitting.
An insert occupies space within the existing opening. Have the installer verify that the selected connection and resulting drainage arrangement meet the applicable requirements. This guide does not promise that every inside-fit product is accepted or performs identically.
Metal ring and plastic body are separate choices
The ring carries the closet-bolt locations and the floor attachment, while the outlet connects to the drainage system. Identify both materials when comparing a product.
Oatey’s 43513 family example (oatey.com) combines a PVC connection with a movable metal ring. That is a different configuration from the all-plastic-ring 43503. The term metal does not by itself establish that a particular ring is stainless steel.
Look for the exact ring material, movement or alignment feature and model-specific drawing. A stainless ring, painted ring and plastic ring are not interchangeable descriptions, and none makes an unsuitable pipe connection correct.
For repair work, first establish whether only the bolt ring has failed or the body, connection or supporting floor is also damaged. A repair ring cannot by itself correct a cracked outlet or a failed pipe seal.
Set the height using the completed floor assembly
Plan the floor finish before cutting pipe or permanently fixing the flange. The flange’s installed relationship to the finished floor and toilet seal matters more than a measurement from unfinished subfloor.
Oatey’s current linked instruction sheet (media.oatey.com) shows the flange supported flush with or on top of the finished floor and fastened through that finish into the subfloor. Confirm the exact model’s instructions and the complete floor construction.
Choose screws or anchors for the actual sound support. A surface tile, loose patch or deteriorated subfloor is not a substitute for the specified anchorage. Have damaged floor material corrected before resetting the toilet.
Our low-flange guide explains the related repair problem. Do not use extra wax as the sole response to an unresolved flange height or moving assembly.
Check toilet alignment and clearance before a permanent connection. An offset product is another design choice; our offset-flange guide covers that category separately.
Joining, testing and setting the toilet need exact instructions
Use the flange, pipe and joining-product instructions together. Select the appropriate cement and any required preparation for the actual material and connection; do not transfer a generic PVC example to ABS or a gasketed iron-body product.
Confirm the specified fit, application method and cure conditions before testing or using the assembly. There is no universal primer, cure-time or pressure-test procedure in this guide.
Keep test-cap and testing instructions with the exact model. The presence of a cap does not authorize an unapproved test method or eliminate the need to remove it correctly before service.
Then use the appropriate new bowl seal and closet-bolt arrangement for the toilet and flange. Our wax-ring replacement guide covers related setting work. The seal should not be asked to stabilize a rocking toilet or replace failed floor attachment.
A practical flange order checklist
- Identify the pipe. Material, nominal size, condition and actual connection surface.
- Choose the fit. Inside, over-pipe or spigot according to the exact drawing.
- Check the body and ring. Record both materials and the model number.
- Confirm acceptance. Installed configuration and any applicable listing limitations.
- Plan the floor. Finished height, sound support and specified fasteners.
- Order the complete job. Compatible joining materials, seal, bolts and any separate components.
Have an uncertain old-pipe connection or damaged floor assessed before purchase. A flange can match the nominal pipe size while still being unsuitable for the actual opening.
Frequently asked questions
Does a 3-by-4 flange fit inside either pipe size?
Not necessarily. Oatey 43503 fits over 3-inch or inside 4-inch pipe. Its connection differs from the inside-3-inch 43506.
Is every replacement flange for cast-iron pipe made of iron?
No. The intended pipe material and flange body material are separate details. Check the exact product specification.
Does a metal ring mean the whole flange is metal?
No. A flange can combine a plastic body with a metal ring. Identify both materials and the exact ring type.
Can I use a plastic inside-fit flange anywhere it physically fits?
No. Check the model’s permitted use, pipe condition, drainage configuration and applicable approval requirements.
Can a thicker wax ring fix a loose flange?
No. Resolve the flange attachment, floor support and height before selecting the toilet seal.
How we chose
This document-based comparison makes no hands-on testing claim. We read current maker pages and linked flange documents, visually checked Oatey’s floor/anchoring instruction sheet, and separated product material from intended pipe material. On October 14, 2026, both linked standard new offers showed stock with exact model and part fields: 43503 from Amazon.com and 43506 from bestbrandsupply. Confirm delivered model instructions and applicable requirements. Read our selection method and about Plumbing Picks.
Primary sources
- Oatey 43503 (oatey.com): exact PVC/plastic-ring identity and connection; inconsistent mounting-hole counts not repeated.
- Oatey 43506 (oatey.com): ABS inside-fit identity; generic web listing badges not treated as acceptance proof.
- Current linked Oatey Level-Fit submittal, August 2019 (media.oatey.com): exact selector, fit and Inside Fit UPC limitation.
- Current linked Oatey instruction sheet, July 2020 (media.oatey.com): finished-floor and structural attachment context; no universal primer/cement procedure transferred.
- Sioux Chief 886-GI (siouxchief.com): cast-iron body example, not a verified retail offer.
- Current linked PushTite sheet, February 2017 (cdn.siouxchief.com): specific gasket connection and body codes; not every iron flange joining method.
- Oatey 43513 (oatey.com): separate metal-ring/PVC configuration; no unsupported stainless claim.