Risco RWT62W86800C Wireless Shock and ContactFor extra security, we would recommend that you have a combined shock detection contact installed on any vulnerable doors and windows (that you will not use to enter or exit via when setting or unsetting the alarm system). These are ideal for protecting patio doors, french doors and conservatory doors. Once the system is set the alarm will activate as soon as the door or window is opened or when it detects a shock (e. g. someone trying to force entry).