The Protech by Hirsch SDI-77XL-MIL-D PIRAMID is a high-security, dual-technology outdoor motion sensor engineered for demanding perimeter protection applications requiring precise, narrow-beam coverage. Approved by the USAF for Protection Level 1 Nuclear & Below, this MIL-spec sensor delivers a focused 100 ft. x 10 ft. (30 m x 3 m) narrow-beam detection pattern using Lens D, making it the ideal choice for corridor-style perimeters, fence lines, alleyways, and confined approaches where a tight, controlled detection zone is critical. Combining PROTECH's proprietary Stereo Doppler microwave technology with a dual-element passive infrared sensor in an "And Gated" configuration, the SDI-77XL-MIL-D achieves a probability of detection greater than 0.95 while maintaining an exceptionally low nuisance alarm rate of less than 1 per unit per year. Enhanced detection parameters enable reliable identification of slow-moving, fast-moving, and crawling intruders across the full length of the narrow detection corridor. Ten-position digital range and sensitivity controls allow precise field tuning, while balanced temperature compensation automatically adjusts both technologies to maintain performance from -40°F to +158°F (-40°C to +70°C). Housed in a rugged metal enclosure with a protective weather shroud, the sensor features a user-selectable solid-state Form C relay output, tamper switch, and swivel mounting with 180° horizontal and 90° vertical adjustment. Operating on 10.5 to 28 VDC at just 100 mA (LEDs off), the SDI-77XL-MIL-D is the trusted choice for military installations, nuclear facilities, correctional centers, and any high-security perimeter demanding false-alarm-free, narrow-beam intrusion detection along defined corridors and fence lines.