PREMIUM MATERIAL: These gutter strainers are made of non-corrosive and waterproof Aluminum, which is not affected by weather and robust for long-term use. EASY TO USE: All you have to do is roll this downspout mesh filter up tighter before inserting and it will expand in place after you put it in, without taking any professional tool of skill. PRACTICAL TOOL: Dense mesh filter can prevent leaves, debris and roof moss form clogging downspout pipes as well as block critters from climbing up in. APPLICATIONS: Suitable for outdoor, rooftop terrace and other ground water demand. NOTES: Be aware of wearing gloves when you work with these strainer mesh, for the sharp edge may cause scratches. We recommend you check around the downspouts periodically to remove to whats building up in case the water overflows.