20 g to 12 g CO2 cartridge adaptor

This thing lets you use 12 g gun CO2 cartridge instead of a 20 g bicycle cartridge in the pump. Works with pump that has a non-threaded pump head (cartridge is just pressed in, not threaded). Basically this thing fills the empty space left from 20 g cartridge and ensures that 12 g cartridge is pressed tight into the pump head.