2002 VF Autococker
WGP Swing Trigger
WGP Black Magic Venturi Bolt
Freak Barrel System w/ 12 Freak front
None really, although I am sure compared to more expensive bolts there are
I grabbed this bolt off of eBay for a good deal. Definitely an upgrade over the stock bolt as I have noticed better consistency in ball velocity and trajectory. Obviously this bolt is not the best out there, but for the price I do not think it can be beat. One neat feature I found on it is a little indent for where the ball detent would rub the bolt; this prevents undo wear on both the bolt and detent. Other bolts I have seen do not have this feature.
If your looking to upgrade your cocker and don't (a) have a wallet full of Hamiltons, and (b) aren't looking to lay $40 worth of paint in 2 seconds (e.g. aren't looking to shoot >12bps) then this is the bolt for you!