Original Apple single foot release actuator and spring for all the Macintosh PowerBook 190, 5300, 3400c (M3553 Hooper) and original PowerBook G3 (M3553 Kanga) series. This is usually supplied as part of the chassis/CPU stiffener but it can be fitted separately if needed. There is a tab on the chassis which when pulled back allows the actuator and spring to lift out.