Only cost me 3 quid off ebay with free postage and easy to fit (2 wires). It'll give me peace of mind when I've got stuff like heated jacket etc running from my battery. It'll also give me a heads up if battery is going duff or not recharging. It's curently showing 12.5v with engine off, 13v at tick-over and 16v on motorway. Nice to know info
