Pre-assembled XVM tower lights have wires with wiring instructions labels. Each signal unit in a tower light can be identified by a different wire color. Electrical connections between units are made automatically. Built-in buzzer (80 db) in base unit Fully interchangeable light sources: incandescent lamp lighting or flashing, LED Modular unit stacked vertically Complete indicator bank included (assembled and wired): Mounts on support tube with bracket or support tube with plastic fixing plate (Length 100, 250, 400 mm).