Compact wireless mini magnetic detector Jablotron JA-155M for monitoring door and window openings. Operates on 868.1 MHz (JABLOTRON protocol) with bidirectional communication; compatible with JA‑102K, JA‑103K, JA‑107K, JA‑152KR and newer JA‑100 panels. Powered by 1×CR2032 (not included); typical battery life 2 years.