This 5"x 5" Packard Ideal pneumatic shutter has a large 2 11/16" opening. I used it as an auxiliary shutter in front of my camera when doing multiple exposures. In that way, I never touched the camera during exposures. I have a 3/8" aluminum rod attached to it so I could easily position it in front of my lens with Matthews grip equipment. The Matthews grip equipment is not included. The aluminum rod unscrews from the shutter via two small screws. Included with the shutter is 6' of air hose and a relatively new bulb. Of course, the system works quite well.