Middle A uses the structure of the combination,does not use any bolt, the contour is artistic, the structure science, the installment disassemblage  is canvenient: As the pitch adjuets willfully take 50MM,each level can afford 400kgs at most; The surface uses the static electricity to spurt modelsprocessing', anticorrosion rust prevention, firm durable; Widely applies in the supermarket,the enterprise warehouse and the Institution .