【Product Overview】 This wireless door/window entry alarm is a convenient device for enhancing home and office security. Model (BL-8513) 【Materials and Size】 This product is made of PS and POM materials, ensuring durability. The size is W3.4 x D2.2 x H9.2cm, featuring a compact design. 【Functions and Usage】 It can be easily installed wirelessly and detects the opening and closing of doors and windows, triggering an alarm. It is ideal for entrances and exits in homes and offices to enhance security. - Model Number: BL-8513 - Materials: PS, POM - Size: W3.4 x D2.2 x H9.2cm - Function: Wireless door/window entry alarm Thank you for viewing. Brand new, unused. Compatible with sliding windows. Please purchase all four together.