Zoo Med's Terrarium Mesh is a non-toxic mesh designed for use between substrate layers. When used above Zoo Med HydroBalls, it allows proper water drainage which keeps substrates from mixing and contaminating the water filtration system. Excellent for use with waterfall applications. Non-toxic mesh designed for use between substrate layers Allows water drainage Helps keep substrates from mixing Available Size: 18" x 18" (46cm x 46cm)