We have introduced this smaller pulley ( 5% smaller ) for fast running 60HZ machines. The 401 does have scope to slow the speed by lowering the magnet but some machines even with the magnet down to the maximum still run fast. The lower the magnet goes down towards the eddy disc the more the deck is harder to stabilise the speed.
This smaller pulley will give the owner more scope to control the speed
This pulley has the clamp as standard