The Gemini low profile wireless window/door transmitter virtually disappears in slimline window frames. Expand your Napco Gemini Security system with these seamless components to customize a reliable system - flexible enough to help you meet the most modest of budgets yet expansive enough so you can secure even the most demanding of applications requirements. FEATURES: New super compact design 2.5 x 1 x 0.4 (HxWxD inches). Tamper supervised. Replaceable lithium PL2032 coin cell battery (supplied). 5-year battery life typical. Magnet and Internal reed switch. External lead (24-inch mini connector pigtail) for wiring external devices (jumper-selectable). Magnet mounts with either supplied double-face tape or screws (screwtabs snap off mounting plate).