Micro expanded metal can be used individually or used combined with woven wire mesh as gutter filter. It can block falling leaves entering and blocking the gutter. The meshes permit air, sunlight and rain passing through to ensure the gutter dry and clean. Additional, the small meshes of expanded metal and woven wire mesh can keep out wasps and other pests. When you use it, just fasten them on existing rain gutters, no need to replace existing rain gutter.