Security Door/Window Alarm Opening Detector x 2 ● For home, office, and store security! ● Prevents intrusion through frequently used doors and windows, which are often targeted. ● Alarm activates when opened! ● High volume 90dB ● Easy installation with included double-sided tape, no wiring required ● Battery operated, uses 2 AAA alkaline batteries (sold separately) Shipped via Yu-Yu Mercari.