The series of holes in the inner and outer setcions of the pulley are arranged so that as the locking pin (shown) is moved from hole to hole, the pulley indexes exactly 1 Cam degree.

The central hole (Where the pin is in the picture) is the zero position, the holes allow up to +/- 10 degrees movement.

This allows fast accurate swinging of the cam timing when setting up on the Dyno/Rolling road therefore saving time & money.

When untertaking a dummy build of your engine the holes can easily be marked to indicate which holes are 'Valve Safe', the positive positioning giving more confidence when undertaking changes in cam timing.

The outer part of the pulley is 'Hard' Anodised which is much less suseptable to wear than other manufacturers decorative red/blue finishes therefore giving the pulley a greater lifespan.

And a final small but important design feature is the change to std Hex headed bolts that are less likely to 'Round Off' than allen key headed screws.