Wireless door stop alarms offer a simple yet effective security solutionr just insert a 9v battery adjust sensitivity and switch onr quick set up with no installation requiredr great for use in flats or shared housesr just 13cm in lengthr features durable stainless steel coverr intruders will trigger a120db high pitched sirenr 2x wireless door stop alarms for 899 pound instead of 1998 pound save 55r 4x wirelessdoor stop alarms for 1699 pound instead of 39