Security Boss MaxSeal Sash Lockable Window InsertDescription Security Boss MaxSeal Sash Lockable Window Insert Dual Flap Pet Door For the best insulation and sealing in a window pet door, choose the MaxSeal Sash Window Pet Door. The MaxSeal Pet Door, Dual Flexible Flap Model is the pet door used in this device; it is easy for pets to use while offering a nearly perfect weather barrier in the harshest environments. The Insulated security panel slides from the side, locking the pet opening. All