Medium type (B) rack（long span）:
Locked by butterfly hole structure and cargo dead weight, larger bearing capacity than type (A); esay assembly and disassembly; limitless connection to main auxiliary rack; enhanced rack robustness; saved investment; layer plates arbitrarily adjustable at 75mm steps; steel, wood and other layer plates can be used; Rack consisting of column disc, crossbeams, crossbeams, layer plates, safety pins and plastic footing.