This Harmony XB5 40mm mushroom button is black, works with locked key release mechanism (key no. 455). It has a round shape and a plastic bezel. This 40mm mushroom-shaped push button head is ideal for situations where quick actions are required for a process or machine to function correctly. Or where operator movements require maximum ergonomics. It combines easily with the Harmony series contact blocks to perform a variety of control functions. A distinctive 40mm mushroom shape makes it visually clear from a distance. Thanks to its IP66 protection rating, it is shockproof, dustproof, waterproof and vibration resistant, making it ideal for use in harsh environments.