Stroke and vibration detector via unidirectional radio, frequency 868Mhz. 24-hour perimeter protection detector designed for indoor applications. It uses its ability to analyze vibrations, detects entry attempts when there is an attempt to force, break, drill or see through the protected window, door, wall or ceiling. CR123 3V lithium battery included. Compatible with RISCO™ unidirectional and bidirectional wireless systems.