So how this works, is it is an add-on to the remote detonator, where you can point and click at specific bombs and change them to a proximity mode, blowing up when someone is in their blast radius.
This helps everybody, as griefers can push people off of skybases easier, you can make defense with them on the sides of skybases, and in general you can let off smokebombs to hide from taggers if they get too close to you, or just make a trap (for funny).
Once you buy this, there is now a smaller button on the side you can press to turn the button green, and enter proximity mode for whatever you point and click at.
This costs 800 Butt-coins, and the remote now costs 200 fluff since there's an extra add-on now. (it's easier to make only one available in the inventory to reduce confusion btw.)