Somehow it's not clear that this bulkhead fitting accepts 1.5 threaded ABS on one side, and 1.5 glued ABS pipe on the other. The end shown with a nut is the GLUE end, the inside of the flange end is THREADED. Glue a pipe on one side, screw a threaded fitting on the other, continue with ABS. The washer has ribs for a better seal on uneven surfaces but won't work on a round tank. Remember 1.5 pipe is INSIDE DIAMETER, the outside of the pipe is larger. That's why this fitting seems so large: 1.5 plus schedule 40 thickness plus the fitting walls plus the flange. The inside of the glue end measures 1-29/32, the flange is 3-13/32, the outer threads (the hole you have to drill) are 2-11/32.There. That answers all the questions I had before I bought it. Just what the doctor ordered for putting a drain pipe through the floor of my trailer. But you're probably buying it for something else!
Rating: [5 of 5 Stars!]