SKLZ Power Handle* Bat Handle Resistance Trainer Strengthen Core Hitting Muscles For Explosive Power At The Plate! The SKLZ Power Handle provides swing resistance, which helps build upper body strength and core rotational speed--keys to increasing your swing speed and power. SKLZ Power Handle* Bat Handle Resistance Trainer features: Develops core rotational speed and power Provides resistance training for increasing arm, forearm and core strength Durable elastic band Indoor/outdoor anchor system Door anchor Fence anchor Aluminum bat handle Power Handle... Become A Better Hitter!