The Metolius rock rings will help you get strong without taking up too much space and tucking away when not in use. The free rotating design allows for exercises that are not possible with pull up bars or hang-boards.
Key Features:

• Innovative, portable training device
• Two independent units, each with flexible, single point suspension; allows rotation of joints for injury prevention
• The master is CNC milled for perfect symmetry
• Fine texture
• Large jug on top; deep, incut 4-finger pocket; 4-finger flat edge, 3-finger pocket
• Includes comprehensive instruction and training guide
• 7.25" x 5.75"x 2.25" (184 mm x 146 mm x 57 mm)
• Set of two: 4 lbs. 2 oz. (1.9 kg)
• Sold in sets of two, feel free to use 1 if you are strong enough
• Colors: blue/blue swirl, black/white swirl, brown solid, green/green swirl - sorry no choice.