A housing can be mounted to a pistol or other weapon and conveniently fired therefrom and can be used as a discrete weapon itself. A cap has a central aperture which secures the nozzle and/or valve stem of a canister of chemical irritant from movement and is secured to the proximal end of a hollow tube. A feature of the new invention is a slot access running along the length of the tube for some distance from its distal end. The tube may be either open or closed at its distal end. Toward the distal end of the tube, an interior ridge or stop cooperates with the cap aperture to secure the canister of irritant. When a canister is installed in the housing, the operator can release an irritant spray axially from the canister by pressing a digit against the side of the canister's storage cylinder and, thereby, displace its longitudinal axis along an arc. The housing need have no other mechanisms, except the housing and canister. This method also allows for convenient triggering of a spray from a canister within the housing when the housing is secured under or adjacent to the barrel of a handgun. In some embodiments an actuator compresses against a spring-loaded pusher to contact the side of the storage cylinder and move the longitudinal axis of the storage cylinder to release a spray.