The 300 Cat Door from Staywell is suitable for cats up to 15lbs. Staywell 300 Cat Door 4Way White with tunnel, comes with a transparent flap. 4 way security lock keeps strays out. Suitable for doors up to 50mm (2"""") thick with universal fitting.Optional Tunnels are available for installation through walls. Dimensions: Flap size : 241mm x 252mm, Pet Max shoulder width : 150mm.