Get RX'd Bolt-In Light Bulb Grips provide a different kind of challenge to your grip strength and add an obstacle course element to your training. Light Bulbs can be attached in a number of different sequences around your rig. Attach them along the square cross bars of your Builder® rig and you have a quick obstacle course with lateral movement. The Light Bulbs can also be attached along the upright of your rig to climb up and down the upright height.