Slot-Screen-Perforated Pipe Bridge slot screen have bridge opening arranged in rows and are staggered to reduce the negative effect on the screen's strength. Typically the slots are punched in a flat sheet that is subsequently rolled into a tube and welded. The sand and gravel can't easily block the slot because of the special bridge style design. This kind of slot screen has great mechanical strength and water entering capacity. Meanwhile, bridge slot screens are light, cheap and easily operating. Regarded as the best choice of well tube filter, they are widely applied in a variety of fields in the developed countries.