Plenty of generic rivals sit in this slot; the medial bell detectors & alarms is the one that behaves. At a glance Type: Medial Bell Power: Hardwired Sensor: Photoelectric Compliance: EN 54 Price: à§³26.83 (offer à§³23.48) Why it holds up Set up as a medial bell-class unit, it does the job without asking you to improvise. In practice Care: a rinse and dry cycle in the usual rhythm keeps it looking fresh. First use: no break-in ritual required beyond a quick wipe and a glance at the label. Storage: stows neatly, taking no more room than a loaf tin when out of service. Reasonable to buy, easy to live with, boring in exactly the right way.