[four-door integrated] four rows of 9 layers heightening (32 pairs of shoes +4 pairs of boots can be placed) [bottom pulley] double-row 9-layer heightening (16 pairs of shoes +2 pairs of boots can be placed) [upgrade and widen] double-row 9-layer heightening (about 18-27 pairs of shoes and boots) [upgrade and widen] three rows of 9-layer heightening (about 27-36 pairs of shoes and boots) [four-door integrated] four rows of 9 layers (36 pairs of shoes can be placed) [two-door integration] double row 9 layers (18 pairs of shoes can be placed) [upgrade and widen] double row 9 layers (about 18-27 pairs of shoes) [upgrade and widen] three rows of 9 layers (about 27-36 pairs of shoes) [four-door integrated] four rows and 6 layers (24 pairs of shoes can be placed) [two-door integration] double row 6 layers (12 pairs of shoes can be placed) [upgrade and widen] double row 6 layers (about 12-18 pairs of shoes) [upgrade and widen] three rows of 6 layers (about 18-24 pairs of shoes) [four-door integrated] four rows and 6 layers heightening (20 pairs of shoes +4 pairs of boots can be placed) [bottom pulley] double row 6 layers heightening (can put 10 pairs of shoes +2 pairs of boots) [upgrade and widen] double-row 6-layer heightening (about 12-18 pairs of shoes and boots) [upgrade and widen] three rows of 6-layer heightening (about 18-24 pairs of shoes and boots) [four-door integrated] four rows and three layers heightening (8 pairs of shoes +4 pairs of boots can be placed) [bottom pulley] double row 3 layers heightening (can put 4 pairs of shoes +2 pairs of boots) [upgrade and widen] double-row 3-layer heightening (about 6-9 pairs of shoes) [upgrade and widen] three-row 3-layer heightening (about 9-12 pairs of shoes)

multiple choices (see the corresponding picture)