Fluker Labs SFK38008 Metal Screen Cover for Pet Habitat, 18 by 36-Inch Screen cover creates a secure and stable environment for any pet Made of a durable metal This unique cover withstands high temperatures from heating devices The metal mesh screen also increases the tank air circulation, minimizing unwanted growth of mold, bacteria and other organisms in your tank Measures 36-inch length by 18-inch width by 1-inch height; Fit for 40-gallon tank size