Home → Tank Trailer Products → Gaskets → Flange Gaskets → TTMA → Drain Sump → PTFE Envelope → Square Type PTFE Envelope → TTMA Sump Gasket - 4" - Square Cut PTFE Envelope w/ Non-Asbestos Filler - 1/8" Thick White N/A- Special 6-1/8" ID (20/Pack)