Alan Kirk send this review of Micron M bite alarms.

These bite alarms are superb for the money and at £20 these alarms cannot be passed by if you need a new Alarm.
The features include a jack plug for sounder boxes, magnet roller wheel, red bright LED and a volume control button. It can be really quiet if you want it to be or if you want to show off then you can turn it to full blast and it sounds great when you get a screaming run. The protective cover is on your "needed" list because it gets turned on easily in the protective bag you keep it in, and for only a fiver the protective cover stops the battery being wasted. This has to be on your buzz bars because of its price and great value for money.