LED is "OFF" PHOTO: AX-200ALPHA Fine Adjustment Twin Synchronized Pulsed Beams Designed for Greater Stability > LED is "ON"LED is "OFF" 99.5% Beam Blocking Stability > Beam Stacking 2 Beam Long Distance Stacking Fine Adjustment A.G.C. (Automatic Gain Control) Circuit > Fine Angle Adjustment for Alignment Adjustable Beam Interruption Period ѱ > Frost & Dew Protection Rain, Dust & Insect Protection Lightning & Surge Protection High Grade Aspherical Lens Highly Durable & Heat-Resistant Housing Cover & Chassis Form C Relay Providing More Flexibility Stainless Steel Screws & Back Plate >