SKLZ Core Pushup Strength Trainer Maximize Upper Body & Core Strength! Increase the intensity of pushups and planks and maximize upper body and core strength with the Core Pushup instability trainer. The steel platform and balance ball combination create an unstable surface for a variety of strength training exercises including 7 configurations printed directly on the platform. The durable balance ball inflates/deflates for variable difficulty. SKLZ Core Pushup Strength Trainer features: Effectively engage entire body 7 illustrated exercises printed on the platform Durable balance ball inflates/deflates for variable difficulty Pro-grade steel construction for high-intensity workouts Durable, molded comfort handles Ball and pump with needle included Core Pushup Trainer... Improve Strength & Balance!