2gig DW20R Recessed Door Contact ETL Listed<div style="text-align: left;"><strong>[Product Information]</strong><br><ul><li>Compact size， only 2 ½ in. long</li><li>Fully supervised</li><li>Lithium battery with 5 years life</li><li>Reed sensitivity: 0.625 in. (1.59 cm) minimum gap， 0.85 in. (2.16 cm) typical</li></ul></div><img src="http://ecx.images-amazon.com/images/I/21Y7QR0kkbL.jpg" noproxy>