hidden lock roof plate 1.durable,low cost 2.flat and smooth,corrugating 3.high utilization rate,tenacity,degree of production HV-373 plate is categorized as hidden lock walling material.When installed,mechanical bolts are hidden,not destroying the superficial technique.It is flat and smooth,even corrugating.With high utilization rate,tenacity,degree of production automation,low cost,it is very ...