Flylock Double Ivory Celluloid Columbian Steel Tank Co automatic knife

Antique Flylock Double Ivory Celluloid Columbian Steel Tank Co automatic knife was made by the Flylock Knife Co, a division of Challenge Cutlery Corp of Bridgeport, CT in the 1920s. It's the larger size of the two bladed switchblades that the company made measuring 3 3/8" closed and 7 inches with both blades open. Each blades is activated by sliding an oval button, one on each side of the knife. The blades are mostly full (90% or better) with patina, scratches, light pitting and some peppering. The both blades stamped Flylock over REG US PAT OFF on the front. Back tang of the big blade is stamped THE FLYLOCK arched over KNIFE CO over B'PORT CONN small back tang is stamped US PAT MARCH 5 1918.  The scales (handles) are Ivory celluloid and are in good condition and have advertising for COLUMBIAN STEEL TANK CO KANSAS CITY, USA on the backside and the front reads: CR GALLAGHER & COMPANY 806 WRIGHT & CALLENDER BLDG LOS ANGELES, CALIFORNIA. The knife functions well with both blade tips below the liners closed and both open fully with good average lockup when open. Does rattle when shaken with blades open. Small blade has kickback. Nice 100 year old American double switchblade. VG+ condition.