This nut has a larger hexagon which is 21mm across flats and is specially designed to suit a spark plug spanner. It fits the standard 17mm axle on Sherco, Montesa & Scorpa trials bikes and reduces the number of tools you need to carry in your bum bag.
CNC machined from billet 7075 T6 Ergal Aluminium alloy. M17 x 1.5 mm pitch