NT-M18 Size: 18" x 18" Features: -Terrarium mesh. -Non toxic mesh. -For use in terrariums above the hydro balls layer to allow proper water drainage. -Keeps substrates from mixing and contaminating the water/filtration system. Product Type: -Sand, Gravel, & Substrates. Pet Category: -Reptile. Color: -Blacks & Grays. Generic Dimensions: -12 W x 12 D. -18 W x 18 D.