Here is the same kit that I use for making my amplifier and big three chassis grounds. 

This is a kit containing the following items:
1/4" drill bit
Ultimate grounding wire brush
13mm or 1/2" nut driver
Zinc grounding bolts

Here is how you use it:
Drill a 1/4" hole in the metal you are grounding to
Use the wire brush to scrape the paint off around your hole
Use nut driver to screw the ground down. This will not be easy to do by hand, it will be cutting its own threads. I use a power drill to do this. 
 
I offer this kit with different amounts of grounding bolts to help out everyone from the DIY installer to the professional installer. 

The DIY Kit comes with 3 ground bolts. One for your amps in the back, and one you may need for your big three chassis ground or another vehicles amp install.

The Pro Kit comes with 12 ground bolts. When you use all  of them please come back to refill your grounding bolts.