This kit is CNC Laser cut from 3/16 steel plate, which makes it perfect for notching a Full Size or Mini truck frame. The side plates, upper and lower caps are extra long so you can cut them to your desired length. Sold as an 8-piece weld together kit. The measurements are 12" tall, 12" wide at the top, 15" wide at the bottom, 7" wide at the inside bottom, 5" wide at the inside top. This notch will give you 8" of more axle clearance.