12 Space Rack Stand. Samson's rugged equipment racks are solid steel and feature fully enclosed steel side panels. They are available in four sizes: 8-space (SRK8), 12-space (SRK12), 16-space (SRK16) and 21-space (SRK21). The racks are set upon 4 heavy-duty, 3-inch (75 mm) casters with locking fronts. Each Samson equipment rack includes a single-space, flanged blank panel. The truly innovative thing is that the unique steel support bar construction allows the racks to be assembled to accept either the European or US thread sizes.