I typically make my own. I bend a piece of 14 gauge steel into a small angle (5/8" x 3/8"), and make hooks from 3/16" rod. I make the angle long enough to suit the battery (3/16" clearance hole in each end), and bend a dog-leg in the rear hook so that it reaches the hole in the rear of the tray. The hooks are threaded 10-24, and I use nyloc nuts to secure it. Works a treat.