sweller wrote[QUOTE] It seems to use a magnet to attach itself to the sprocket - a reasonably safe assumption that will be square to the wheel - so your B&Q special will need to be square and small enough for you to attach to the sprocket.[/QUOTE] So would one of them ex burglar alarm bar magnets what live in the drawer in the kitchen on the off chance they will one day be useful gaffa taped to the illegal laser pointer thing I got when I went to merkainia a few years back what I have got lying in the back of the same drawer be any good?