1mm thick aluminium cylinder head spacer for 125/200/250/280/300 Pro models...come complete with a new set of head orings. Simply sandwich the spacer between your cylinder and head. A thin smear of 'Blue Hylomar' is advisable on top of the cylinder whilst fitting....These spacers will smooth out the initial power delivery and works very well on all Pro models....Fit this togther with a slow action throttle for a cheap and easy way of changing the performance of your Pro! May need de-burring when you recieve this part because they are waterjet cut which leaves a few burrs on the spacers....easily remove with a small file....Flywheel weights for all models also available!