Mains with battery back up. Low battery and fault warning light. Peak level button. Audible and visual alarms. Test/reset button. Can be used as a direct plug-in, a wall mounted or a tabletop unit. Continuous digital display. Cord length 2.05mSize: H14 x W9 x D4cm
CommentsGood points: Alarm triggered within three minutes and noise level was over 85db during testing. In case of a power cut the 9v battery will continue operating the alarm for at least 20 hours. Clear easy to read display. Thorough instructions. Drawbacks: Quite bulky. Should only be used as a plug-in unit if the socket is around shoulder level.