Black, X-heavy. The Cando flexible hand bar exerciser is a lightweight, portable exerciser designed to strengthen muscles in the hand, wrist and shoulder. Also promotes coordination and increases range-of-motion. Perform oscillation movements for neuromuscular and balance training. Use for soft tissue and joint mobilization. The rubber bar utilizes the same graduated progressive color code as other Cando products (tan, yellow, red, green, blue, and black). Consistent bar diameter and length throughout resistances means you use the same muscles with each resistance.