12 2" Backpressure Caps for Remote Firing or Air Confetti Canons Backpressure Caps - Backpressure caps are essential for the efficient operation of your confetti launcher. Seal them around the top of your launcher with a piece of masking tape. This causes the pressure to build up before shooting. This in turn causes the confetti load to be ejected more forcefully resulting in more height and a better looking display.