t4e umarex hds .68cal double barrel paintball/rubber balls marker (7.5 joules) w/free 20 .68cal rubberballs t4e the new hds double-barreled marker .68cal from t4e combines power and speed. thanks to its co2 quick-piercing system it’s ready to use at any time. with a light blow on the bottom of the grip you can puncture the co2 capsule whenever the occasion demands. the hds comes with a picatinny rail under the barrel. the large .68 caliber allows you to use rubber balls, chalk balls and paintball, which can be shot individually or simultaneously from both barrels.