Features The Smart-Rail can unlock and pivot to provide better standing support with less reaching and twisting. To use, simply slide the support frame (24"W x 32"L) between the box spring and mattress, secure with safety straps, and set the rail height. The rail measures 30"H x 16"W , which fits nearly all beds, from twin to king size.Specifications- Unlocks and pivots- Fits twin to king size beds- Standard size : 30"H x 16"W- 300-lb weight capacity