4 in 1 Multi-Function: 4 modes to meet your multiple options: general alarm, constant alarm, time delay (closing alarm) and doorbell, just press the button to choose the function you need without no adjustment complicated. This contact sensor kit can quickly detect the status of your door or window. Requires 2 AAA batteries (not included). Freezer Door Alarm with Delay and Widely Use: Upgraded versions with 3/15/30/60 seconds delay to choose from. Magnetic Trigger Door Alarm Sensor Protecting Home Through Window Front Door, suitable for safe, cabinet, freezer, refrigerator, swimming pool sliding door, store, office, apartment, hotel, etc. 108dB Loud Enough For Your Home Security: The door and window alarm helps effectively deter intruders and thieves with a loud 108dB alarm, also the open chime will notify you if children/ pets/seniors arrive or leave unexpected. It can prevent your children from sneaking around. And it is a perfect wireless security magnetic alarm for child safety, burglar, home, garage, mailbox and business security. Easy to Install: This home/window contact sensor alarm kit comes with self-adhesive pads so no tools are required, just stick the door alarm sensor on the door or window. He can also be used as door stopper alarm, pool door alarm, garage door alarm or sliding door alarm. Low-power design, providing practical and long-term protection. They can work for more 2 years. Installation Note: Be sure to close the alarm and the magnetic strip, the installation distance between them should not exceed 2cm. The 2 parts must be aligned by their alignment arrow.