Requirements: Uses 18650. I currently have 2200 and 2600mah batteries. Absolutely firm on the price. I only need the unit itself. I looked up the Smoktech Gripper, but they're out of stock on a few sites, and I think that's the one that had a recall at some point. This is just a backup device, so it doesn't have to be anything fancy. I use cartotanks, so clearo compatible threading is not important. Thanks!