The EM8660 wireless door/window contact is suited for use with the Eminent EM8617/EM8610/EM8615/EM8605 Alarm Systems. The magnetic contact is suitable for doors and windows. The alarm is activated once a closed window or door is opened. The EM8660 works wireless and is powered by 2 CR2021 batteries. Therefore easy to install on every door or window. The EM8660 warns you when the batteries need to be replaced.