Five Oceans 1" NPT Thru-hull Stainless Steel FO-378 PIPE THREAD TYPE - 1" NPT (American National Standard Taper Pipe Thread). MADE FROM high-quality AISI316 Stainless Steel TAPERED for sealing, often without any thread sealant; for connections in nearly every type of service TOTAL LENGTH: 3 1/8" (79mm) FLANGE DIAMETER: 2 1/8" (54mm) FLANGE HOLE THICKNESS: 1/4" (6mm)