This replacement bolt on 4 hole front spring hanger for boat trailers is made out of hot dipped galvanized steel. This hanger can be used as a front hanger on a single axle trailer. Ideally, this 4 Hole Bolt on Leaf Spring Bracket Bolts onto I-Beam Trailer Frames. Also, this can be used as the front and rear hanger on a tandem axle set up. It Simply bolts to the frame of your trailer using 3/8 inch bolts. This spring hanger is used on 1 ¾ inch wide Double Eye spring. The bolts to attach the double eye spring to this hanger would be a 9/16 inch bolt. This Spring Hanger is Very Common on single axle Boat Trailers when using Double Eye Leaf Springs. To select 3/8 inch Diameter Bolts to mount this hanger check out Boat Trailer Bolts. This is just the front hanger on your single axle set-up. We also have the Rear Hanger Available as well as replacement leaf spring shackles available here Boat Trailer Suspension Parts. You also commonly need new If you are using this in your tandem axle set up. This Hanger would be towards the front, and the rear, the third hanger would be slightly longer and attaches to the equalizer bar of the suspension system.