I've got one on the earth lead on mine Martin, which looks very similar to that one apart from the colour. Every now and then it doesn't make a good connection when first clicked on to the battery so it's just a case of undoing it and putting it on again, then it's fine. I thought it was playing up earlier this year, but it doesn't seem to be. Mines the one towards the bottom of this page ( http://www.vehicle-wiring-products.eu/VWP-onlinestore/battconns/battclamps.php ) but oddly they only seem to do them in red or blue now.

Real name: Mike Edwards. Web site: www.firenza.net