The RapidMount PowrGrip 4.5 is an indispensable accessory that lets you mount speed light flashes onto non-porous surfaces such as glass, fiberglass, mirrors, and more in a secure manner. Its vacuum cups make use of a hand-actuated pump to remove air from between the rubber pad and the attaching surface efficiently, thus, providing a hold that is much more reliable and long lasting. The PowrGrip features a red-line indicator that warns if there is any drop in the holding power. Also, the PowrGrip includes a pad protector and a non-reflective black finish.