Crafted of 18 gauge galvanized steel, powder-coated in a flat black finish, Easy Loader Vents provide control of variable airflow for comfortable conditions spring, summer, autumn, and winter. Three 1 1/8" diameter holes allow even ventilation whether open, closed, or ajar. Vents can be purchased as an after-market accessory kit. Kits include an instruction sheet and hardware. Size small will fit the kennel for small trucks (CMDUECE), large will fit the kennel for large trucks (CMDBOX), and extra-large will fit EZ-XL Kennel (NLC2101).