A specially designed grenade launcher used for the TAG Innovation range of grenades only. These are CO2 ready (regulated to 850PSI max).
They don't use a lot of gas at all and are quite amazing just dry-firing them. The bang is VERY loud! The extruded composite plastic sleeve is actually the most expensive part of this launcher and I'm told by Mark at TAG Russia that they are "Strong as a Gods ass!" so that's good enough for us :) Seriously though, you won't break one of these easily at all.
They do however require maintenance from time to time just as any other gas grenade and it's good practice to add a squirt of silicone oil in the gas filler valve every now and then. If the worst does happen and you manage to wear it out or lose bits because you open it up for some reason, we do have the complete internal replacement kits.