The new addition to the Roto Grip HP4 line is the Sinister. Sinister uses the Cage core with 76H Hybrid coverstock. I drilled mine 4.5 x 4 x 4 3/4 or 45 x 4 x 30. I compare the Sinister to the popular Defiant Soul, with more backend motion. But the Sinister is cleaner through the fronts than the Hyper cell. A good combination of both balls. I have used the Sinister with Storm step 2 for league with good success, just can only use it for about a game. I have applied surface to it bowl on Kegel sport conditions, which created a very strong ball motion even on the longer patterns.
Straight players will like the control and hitting power, and the crankers will like it to be able to open up the lane with good continuation. Another great ball from Roto Grip.

Right Hander
PAP - 4 up 1 1/4
Rev rate - 400
Tilt - 15
Speed - 17