OATEY 700-1 P-TRAP 1.25, 20 GAUGE

The Oatey 700-1 is a 1-1/4 inch P-trap, so it suits 1-1/4 inch tubular drain lines, the common size on bathroom lavatories. If your sink tailpiece and wall stub are 1-1/2 inch, which is typical on kitchen sinks and some tubs, you want a 1-1/2 inch trap instead.

20 gauge refers to the tubular wall thickness. It is the heavier of the two common tubular grades, thicker than the 22 gauge used on light residential traps, so it holds up better to repeated disassembly for cleanouts and to the handling a maintenance crew gives it. For an apartment or hotel lavatory that gets snaked regularly, 20 gauge is the one to specify.

A P-trap, which is what the Oatey 700-1 is. P-traps exit horizontally into a wall stub-out and are what plumbing codes accept, because the horizontal arm vents properly. S-traps exit downward through the floor and can siphon the water seal dry, and they are not permitted in new work. If your existing drain comes out of the floor rather than the wall, you need a floor-outlet arrangement, not this trap.

Oatey part number 700-1. Order by that number and you get the 1-1/4 inch, 20 gauge P-trap; Oatey's tubular line uses close part numbers across sizes and gauges, so the suffix matters.