1 BLANK (No Slug) inner sleeves that twists into the bowling ball Does NOT contain outer sleeve Benefits of the Twist: The thread-like feature absorbs the load of the weight and the velocity of the bowling ball delivery; i.e. visualize pulling a nut straight off a bolt without unscrewing it. The Twist cannot be removed from the bowling ball without the inner being rotated 360º Easy to install and superior quality compared to other systems Length: 2 3/4 Hardness: 75