The Sig Sauer® ROMEO4T 1x20mm Ballistic Circle Red Dot Sight features a durable, CNC-machined aircraft aluminum housing, designed to deliver long-lasting strength and corrosion resistance. The illuminated ballistic circle dot reticle offers quick, intuitive target acquisition, activated by MOTAC™ (Motion Activated Illumination System) technology, which automatically activates the illuminated reticle when it senses motion, and powers down the unit when the weapon is idle for reliable battery preservation. SpectraCoat™ lens coatings deliver enhanced color fidelity and light transmission for optimal clarity, while integrated see-through lens covers protect against scratches, bumps, and abrasions during storage and transport.12 user-selectable brightness settings (10 daylight; 2 night vision) ensure reliable visibility in all lighting conditions, while the included true co-witness QR mount and low-profile 1913 Picatinny mount readily attaches to most rail-equipped rifle, carbine, and shotgun platforms for maximum versatility. The side-loading battery compartment makes it easy to replace the CR2032 battery (included) without removing the sight or affecting zero. IPX8 waterproof and fogproof. 100,000-hour battery life.