JOHNSON  Pro 40-6700 One-Sided Laser Detector with Clamp Quickly and accurately locates any laser signal emitted from rotary or "pulsed beam" line-generating laser levels Front display is back-lit Audible and visual indicators for precise leveling Range = 393.7 ft. (120m) radius Automatic shut-off timer and This detector detects red (635/650nm) laser signals.