☞ This is a set of magnetic detecting switch used to protect doors and windows for the most part ☞ Protective device monitors the opening and closure of doors and windows ☞ High quality magnetic sensor contacts with strong magnetic, sensitive respond and long durability ☞ The wired part often be installed on the fixed door frame and the mating part is mounted at the corresponding place on the door ☞ Easy to install and use. A good replacement for the old contacts. Simple to install no hassles