This is Diversi-Tech 2-1/2 inch to 2 inch adapter kit, part number DTADP35. This adapter kit is designed to allow you to use your DTLBM or DTALBM series locking ball mounts from Diversi-Tech in conjunction with your trucks 2-1/2 inch trailer receiver. Included is one adapter sleeve and 1 of Diversi-Techs long span locking hitch pins. You will the adapter into your trucks 2-1/2 inch receiver. You will then the included hitch lock to secure the adapter inside the trucks receiver. Once you have done this, you are ready to use Diversi-Tech Self-Locking Ball Mount. And that does it for the Diversi-Tech 2-1/2 inch to 2 inch adapter kit, part number DTADP35.