ARB Ascent BASE Rack Blade Kit Model 17923050ARB Ascent BASE Rack Blade Kit Model 17923050 ARB's BASE Rack mount kit for the Tacoma Ascent Truck Cap uses proven attachment methods to keep the roof rack as close as practical to the vehicle roof. BASE Rack specific blade brackets suit the 61 in (L) x 46 in (W) (PN 1770160). By incorporating a dovetail extrusion around both the full perimeter and along each edge of the internal beams, the BASE Rack provides endless mounting and attachment options.