CO2 connection kit Use with Umarex Steel Force CO2 rifles Connect to a paintball tank to get more shots per fill Huge savings over buying 12-gram CO2 cartridges * The Umarex Steel Force CO2 rifle uses two 12-gram CO2 cartridges. That can become very expensive. Instead, hook up to a CO2 paintball tank, attach this hose and adapter and shoot longer between fills.