This is a Metra Side Post adapter. For side post batteries commonly found in GM vehicles. The long post adapters are usually for vehicles with the dual battery setup factory. But you should remove your factory one first, before buying this, to determine if you need the short of the long one.

This will screw into your battery, securing the factory power wire, and gives you an extra bolt on the end to secure your extra wiring. This is the correct style battery terminal for side post batteries.