The Byrna SD (Self Defense) is the successor of the Byrna HD. It has been re-engineered for optimal performance. Powered by compressed air (CO2), the Byrna SD shoots .68 caliber round kinetic and/or chemical irritant projectiles that can disable a threat from up to 60-feet away. It is an incredibly powerful and non-lethal self-defense weapon. Ambidextrous controls, zero recoil, and an ergonomic honeycomb patterned grip. The Byrna SD is not classified as a firearm therefore does not require a permit or background check to own. Free shipping to lower 48 states, including California.