Designed to be used with the V-2924A, Expandable Talkback Intercom System, this call button provides quick connection to a designated station. Emergency button transposes a single press of the button into four required closures to generate an emergency class of service call. Fits A Single-Gang Electrical Box, Black "Call" button For Normal Call, Red "Call" Button For Emergency Calls, Built-in Volume Control, Brushed Stainless Steel Wall Plate; SPECIFICATIONS: Mounting: Call button mounts in a single gang electrical box using two screws. Switches: Single pole momentary pushbutton "Normal Call" black cap, Single pole momentary pushbutton with red cap and electronic pulse generator "Emergency Call".; Shipping Weight: 1.0 lb. (.45 kg). Dimensions: 4.5" W x 2.75" H x 2.125" D(11.43 cm x 6.99 cm x 5.4 cm)