XL Rock series aluminum sticks with replaceable nylon sleeves really pack a wallop. They feature the largest diameter (.620 ) of all of the Ahead sticks and are built for optimum sound projection and durability with ergonomically tuned handle diameters. Precision alloy cores provide negligible weight and balance variations. Super-hard replaceable polyurethane covers protect both sticks and gear. Vibration-reduction system reduces hand fatigue. The XL Concert is 16-5/8 long the XL Studio is 16-1/4 . Each features super-short taper covers.