To use the Centro Bulb duster simply fill duster about half way full of the dust of your choice, direct nozzle into crack, crevice, or void and squeeze the bulb. Remove extension if not needed. (Use care to remove nozzle from crack, crevice, hole or void before releasing pressure from bulb after squeezing. By leaving the nozzle inserted into these locations you risk sucking in moisture, dirt or debris that will block the nozzle)