Product information and features: How it works Everyone passing through the control point pushes the button A red light and high tone indicate that you have been selected A green light and a low tone indicates that you have not been selected on this occasion If you know you could be stopped, you won’t take the risk! Features: Battery operation (3 x ‘AA’ Alkaline, supplied)* Clear indication of SEARCH and PASS with daylight visible lights and audible tones Portable or fixed installation. Desk mount, wall mount or hand held Large 2 inch push-button Search percentage ratio adjustable by internal switches Search settings from 0 to 100% in 0.5% steps Random selection is guaranteed to be totally unpredictable