Although a mostly unarmed force, certain units of the Gardaí, such as detective units, the regional support units, and the Emergency Response Unit are commissioned to carry firearms. The original stock of Smith & Wesson Model 10 revolvers are being replaced by the Sig Sauer P226 and Walther P99C semi-automatic pistols. Regional Support Units have Heckler & Koch MP7 sub-machine guns in addition to issue pistols and non-lethal weapons such as tasers and pepper spray. They serve as a first response to back up regular Garda officers in critical situations due to a rise of incidents that involve firearm use. In order to be issued with a firearm, or to carry a firearm whilst on duty, a Garda must be in possession of a valid gun card.