Flylock Small double Etched antique switchblade knife with shackle

Flylock Small double Etched antique switchblade knife with shackle made by the Flylock Knife Co (a division of Challenge Cut Co) of Bridgeport, CT in the 1920s. It measures 2 7/8  & under 5 7/8 inches open with brass liners and nickel silver buttons, shackle & pins. The knife has two blades, each is activated by sliding an oval button, one on each side of the knife. The blades are both full with original finish. The main blade is stamped Flylock REG US PAT OFF and the back tang is stamped FLYLOCK KNIFE CO B'PORT CONN. The small blade has the same front markings as the big blade, but the back is stamped US PAT 3-5-18. The front of the main blade is clearly etched "HILLMAN-COONEY, INC. The scales (handles) are Coffee & Cream celluloid and are in great condition with some handling marks. The knife functions well with no peek when closed, both blades open as they should with excellent lockup open. Small blade has slight kickback. Nice 100 year old American double switchblade. EX condition.