Color classification
Buy "send" the same color single-layer shoe rack
"Upgrade can rotate" Single White/can put 8 shoes
"Upgrade can rotate" single layer Black/can put 8 shoes
[Upgrade rotatable] single gold/can put 8 shoes
"Upgrade can rotate" double white/can put 16 shoes
"Upgrade can rotate" Double Black/can put 16 shoes
[Upgrade Rotatable] Double Gold/16 Shoes
"Upgrade can rotate" three layers of white/can put 24 shoes
"Upgrade can rotate" three layer Black/can put 24 shoes
[Upgrade can rotate] three layer gold/can put 24 shoes