"The Large Roll-A-Ramp Support Stands provide additional support for ramps over 12’ in length and mount easily to side rails underneath Roll-A-Ramp portable and track ramps. The extra-short size adjusts from 15.75"" to 21.5"". The stands attach with included T-handle bolts and bolt nuts and require no tools to install. They can be placed anywhere along the ramp, making them incredibly versatile."