prop device

[Thalia]

I'm only a junior, junior stage manager (read: peon), but I have a thing for special effects. In school, we used a gadget to jerk actors backwards to look as if they'd been shot or punched in the gut. In a ballet production, we used a similar spring-loaded device to snatch veils off dancers in a ghostly bride scene.

I want to use a similar spring-loaded device to snatch velcro'd costumes offstage, but I don't know what to ask for or order. What are the devices called? Thanks.