The Protech by Hirsch SDI-77XL2-C PIRAMID XL2 delivers precision narrow-angle perimeter detection across a focused 125 ft. x 20 ft. (38 m x 6 m) coverage pattern, engineered for long, narrow corridors, fence transition zones, and confined passageways where wider-angle sensors would generate excessive nuisance alarms. This dual-technology sensor combines Protech's proprietary Stereo Doppler microwave with passive infrared in an "And Gate" configuration — both technologies must activate simultaneously to generate an alarm — virtually eliminating false alarms from birds, small animals, vegetation movement, and environmental disturbances. The Lens C module delivers a tightly controlled long-narrow detection lobe that concentrates full detection energy along the corridor length, ensuring no dead zones across the entire 125-foot range. Powered by 10 to 28 VDC with a current draw of just 100 mA at 12 VDC, the SDI-77XL2-C operates reliably in extreme conditions from -40°F to +158°F with 0–100% relative humidity, housed in a rugged IP65-rated metal enclosure with integrated weather shroud. Upgrade to the optional Lens C-Pet for pet-immune applications. Ideal for utilities, oil and gas facilities, correctional perimeters, airports, data centers, and other high-value sites requiring reliable narrow-beam volumetric protection.