nope i definatly mean 3mm !! when i first tried, power on at the ke, led on all the time at 1mm gap. so backed it off till no light at all, turning the hub i moved it in till led flashed, started at about 4mm, at 2mm gap on all the time. so set it to 3mm, wheel on, dropped her down round the block and tacho works. no idea on the gap, it works im happy. except cars gone now to caterham for post build etc