It has a built in PIR motion sensor that will activate the alarm if any movement is detected. 

It is simple to fit, there are no wires to connect, just put the required batteries in(requires 4 AA not supplied).

Alternatively you can use a 6v adapter which you can also use which is not supplied with this unit, fix to a suitable surface 

and turn it on using one of the supplied remote controls.

Ideal for protecting your property against unwelcome intruders. 

Specifications:

Material: Plastic

Size: 12*88*50mm

Color: White

Powered: 4x AA batteries (not included)

Loud: 105 Db alarm

Package included:

1 x Alarm sensor

2 x Remote control

1 x Mount bracket 

Notes:

1.Due to the difference between different monitors,the picture may not reflect the actual color of the item. We guarantee the style is the same as shown in the pictures.

2.Due to the manual measurement and different measurement methods, please allow 1-3cm deviation.Thanks!