With good penetration and a long reception range of up to 300 m (in open field). Easy installation, no wiring required. Simple wall mounting with double-sided adhesive tape or screws. 55 optional built-in tones and 5 adjustable volume levels from 0 to 110 dB. The transmitter is IP55 waterproof. Perfect for office buildings, hotels, private homes, hospitals, etc. LED indicator for ring zone level. Incoming door open alarm for shop/office/home/business. Easy installation, no wiring required. Simple wall mounting with double-sided adhesive tape or screws. 55 optional built-in tones and 5 adjustable volume levels from 0 to 110 dB. The transmitter is waterproof according to IP55. Perfect for office buildings, hotels, apartments, hospitals, etc. Specifications: Reception range: Up to 300 m (open space) Volume: 0-110 dB, 5 adjustable levels Tone: 55 tones Frequency: 433.92 MHz ± 280 kHz Power supply: - Transmitter: 1 x 12 V 23 A battery (NOT INCLUDED) - Receiver: 3 x AAA batteries (NOT