It is a hood stop for a Camaro and I used a 2 1/16" circular hole saw to cut the backing plate from 1/8" aluminum. The backside of the hood stop has a nut on it as well.
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1