US Patent 9249617 Animal door having an adjustable resistance against being opened

Described is an animal door that is movable between a closed position and an open position and that has an adjustable resistance against the door being removed from the closed position to the open position. More specifically, the animal door defines a passageway and includes a flap that is moveable between the closed position and the open position, whereby the flap obstructs the passageway when at the closed position. The animal door generates a magnetic force that generates a resistance against the flap being moved from the closed position to the open position, whereby magnitude of the magnetic force, and thus the resistance, is adjustable.