The key switches of the Harmony XB4 series have a cut-out diameter of 22 mm and offer three positions. The key style is 455, with a switching action that returns to the center position via a spring mechanism. The key removal position is in the middle, and the degree of protection is IP66, IP67, IP69, and IP69K. The switching angle is 45 degrees, and it is not illuminated. This model includes two keys.

These are heads for key switches, specifically from the ZB4-B series. The key removal occurs in the latched position, which is 32 mm high. All heads require a housing or mounting bracket as well as a contact housing. The surface is black with a chrome coating.