Color classification
White layer-no round
Black layer-wheeled model
Style two white double-layer-no wheel
Black One Layer-No Wheels
White layer-with rounds
Style a black double-layer pulley-withdrawable
Style a white double-layer pulley-withdrawable
Style a black double-layer no wheel-drawable
Style a white double layer without wheel-drawable
Style II black double-layer-with wheels
Style two white double-layer-wheel
Style two black double-layer-no wheel