OATEY 31258 Square Nose Toilet Base Plate

Yes, and that's a designed use. The plates stack, with aligning pegs that key one plate into the next so the stack doesn't shift while you set the bowl. Two or three plates raise and stabilize the toilet on a floor that dips, without the shim-and-caulk patchwork. Remember every plate you add raises the bowl above the flange, so bolt length and the wax seal need to make up that distance.

No on both counts. The base plate is a cosmetic and stabilizing plate that sits between the bowl and the floor, above the flange; it makes no seal to the drain. You still need a wax ring or a waxless seal, and if your flange sits below the finished floor after new tile, that's a flange extender ring job, not a base plate job. Stacking base plates raises the bowl further from the flange, which makes a low flange worse rather than better.

A toilet base plate is a thin white ABS plate that sits under the toilet at the floor and hides what the old bowl left behind: stains, discoloration, and a scarred finish ring around the flange. It's a cosmetic and leveling piece, not a seal, so you still set the toilet on a wax ring or equivalent. The Oatey 31258 has a square nose, meaning the front of the plate is squared off rather than rounded, so it reads cleanly against square-front or contemporary bowls.

It's a high impact material, so it takes bolt load and the weight of a china bowl without the brittleness of a thin plastic shim. The plate weighs 0.55 pounds, which tells you it's a solid molded piece rather than a stamped filler. Standard practice still applies: snug the closet nuts alternately and stop when the bowl stops moving, don't crank them.

For turnovers it usually pays for itself. When a toilet has been in place for years, the floor under and around it is discolored, and the new bowl footprint rarely covers the old one exactly. The 31258 hides that ring so you're not patching or replacing flooring in every bathroom just to finish the swap. It's white, so it works against the common white and light-tile floors in multi-family units, and at 0.55 pounds each they're easy to carry in quantity across a run of units.

Order Oatey part number 31258. It ships as a single white square nose plate, one configuration only, so there's no size or finish to specify. If you plan to stack for leveling, order the quantity of plates you need up front, since they're identical and key together.