Perko 1" Thru-Hull Fitting w/ Pipe Thread Bronze. Flange is machined to fit hull and grooved to retain bedding compound. Neck. is threaded to approximately 3/8 inch from flange.. Cast bronze.. Technical Information:. Pipe Size Inches: 1. Mouting Hole Diameter Inches: 1-5/16. Maximum Hull Thickness Inches: 1-7/8. O.D. Flange Inches: 2-3/16. Model Number: 0322DP6PLB. Ship Weight: 4.1/18.0 lbs.. MADE IN THE USA