Develop strength, power, endurance and balance at the same time -- with the Kettlebell & DynaDisc Jr. Proper use requires strength, coordination and practice with a light weight before increasing weight. Kettlebells focus on functional, whole-body conditioning because lifting and controlling a kettlebell engages multiple muscle groups at once. Try Troy's Cast VTX Kettlebell - 10# and get the DynaDisc Jr FREE!!