AMB Particle. I threw a friends and could not keep it on the correct side. 320 grit wetsand. Feels like a cinderblock if kept in box condition.
I ended up going with the Immortal Solid because I thought it would be a little more versitle. So far I really like the ball. I don't have a ton of revs and tend to be speed dominate, stroker. This ball has really allowed me to open the lane up a bit more. 4" pin to pap, pin next to ring, weight hole in thumb quardant.
I left it in box condition. I bowl on well maintained wood lanes and the owner puts out a shot that does include an OOB outside. The ball will save it's energy for the midlane, then make a hard arch back to the pocket. It is pretty strong though, and I could not even imagine this ball with this layout in a high rev bowler.