FMM-101 is a miniature monitor module (a mere 1.3" (3.302 cm) H x 2.75" (6.985 cm) W x 0.5" (1.270 cm) D) used to supervise a Class B (Style B) circuit of dry-contact input devices.
The DKM18 allows for the expansion of a digital call station to increase the number of available keys and LEDs. It makes it easy to select loudspeaker circuits and transmit voice announcements for a n
FMM-1 is a standard-sized module (typically mounts to a 4" [10.16 cm] square box) that supervises either a Class A (Style D) or Class B (Style B) circuit of dry-contact input devices.