A two- or three-bladed rotating device used in a film projector to interrupt the light source while the film is being pulled down into the projector gate.

One blade masks the pull-down while the other blade causes an additional light interruption, increasing the flicker frequency to 48 cycles per second on 35mm film — a level that is not objectionable to the viewer at the recommended screen brightness of 16 foot lamberts (55 candelas per square metre).