The slightest grasping pressure is all that is needed to activate this Grip Switch and encourage the development of gross grip skills. This pneumatic unit comes complete with removable blue handle, clear polyvinyl tubing, switch base, 1/8" (.3cm) connector, and 1/4" (.6cm) adapter. Remove the grip and use as a puff switch. Requires one 9-volt battery (not included). SIZE: 4 3/4"-dia. x 3"H (12 x 8cm).