The 1SKB-R1906 roto molded rack expansion case (with wheels) was designed to add expandability to the new 1SKB-R102, 1SKB-R104, 1SKB-R106 and 1SKB19-R1208 as well as the 1SKB19-R1006(V) and the 1SKB19-R1010(V). The 1SKB-R1906 can even stack on itself (remove the casters from the top one before stacking).