Plastic Oddities PFG600 Fiberglass Shower Stall Drain, Stainless Steel Strainer 4-1/4 diameter stainless steel strainer with removable plastic film V-Shaped coarse threads that are 8 threads per inch Fits over 2 Schedule 40 DWV PVC pipe Receptor base design allows secondary drainage if leaks occur around strainer Sealing and friction gaskets give a positive seal to the shower base