You can actually use the bottom base from the Mini Protank 2 on the full size Protank 1 or 2, they are all interchangeable. This helps fix the problem on devices with stripped 510 threads and also helps to stabilize the tank. If you don't already have a Mini Protank 2, you can find the base for a couple of bucks, online as well as some brick and mortar stores that carry replacement parts.