The Stop & Go Loading Dock Signal Light (SG10) is the most basic and cost effective way to increase dock safety. It's designed for use beside the loading dock door on the outside of the building. A switch and flasher are not included but can be obtained from an electrical contractor or installation professional. The SG10 is most useful in applications where opposing signals are not required. Housing: Safety yellow (durable plastic will not rust, pit or corrode) Power source: 115 volt AC operation (consult factory for other options) Lens diameter: 4-1/2" Measures 11-3/8" height by 6-3/8" width by 3-3/4" depth Shipping weight: 2 lbs per unit