The water flap is an important part of the central air conditioning terminal device, which is matched with the central air conditioner for the function of steam and water separation. The LMDS type flap is a key component of the air-conditioned room and can be used at both high and low wind speeds. It can be made of FRP material or PVC material, featuring low resistance, light weight, high strength, corrosion resistance, aging resistance, good water and gas separation effect, convenient cleaning and durability. JS wave-type retaining plate is made of PVC resin-based PVC water-blocking plate, which maintains the proper rigidity, impact resistance, anti-aging, corrosion-resistant and fireproof of the water retaining plate. Continuous extrusion molding successfully maintains the density of the flap and the precise geometry, and the length of the flap can be arbitrarily determined. The PVC flap can work continuously in the environment of 90 ° C -25 ° C. ABS, glass steel, aluminum alloy.