This is the flexible back support with dual lumbar cradles that help align the spine for better posture. Unlike straight-backed chairs that encourage slouching, the dual cradles lighten pressure off the spine as much as 65%, encouraging proper lorditic curvature. The cradles adjust vertically for optimal fit, applying light pressure to the lumbar region on either side of the spine, similar to a pair of masseuse's palms. Ideal for those who sit for long hours, the support straps to a chair or car seat with hook-and-loop fasteners; a flexible pivot allows each cradle to move with your body as you shift positions, and is ideal for bumpy road conditions. A built-in vibration massage motor allows you to soothe sore back muscles. Ventilated construction keeps your back cool during extended use. Plugs into AC using the included adapter; also plugs into a car's DC adapter. 15 1/2" H x 16 1/2" W x 5" D. (3 lbs.)