The sand and gravel can not easily block the slot because of the special bridge design.It has great mechanical strength and water entering capacity.Meanwhile, it use steel punching technology and rolled in many ways, so it is light, cheap and easily operating.We us cnc to punch, so the slot can change as your requirements.In order to give customers more convenience, we can offer any diameter screens.We also offer galvanized ones to prolong the operational life.Meanwhile, the slot can change according to the real condition of the earth.If you are interested in our product, please contact us, and for more information.