CRC® 02105 Smoke Test® Smoke Detector Tester, 2.5 OzConvenient, easy & safe product to test the functional ability of a smoke detector. It also checks for obstructions or debris which clog detector vents & prevent smoke from properly entering the sensing chamber. 2. 5 oz Smokeless aerosol spray that provides a true functional test for both commercial & residential smoke detectors It also checks for obstructions or debris which clog detector vents & prevent smoke from properly entering the sensing