G Schrade pullball knife advertising

This is an advertising pullball switchblade made by the G Schrade Knife Co of Bridgeport, CT sometime between 1937 and 1956. These made good advertising knives because there's no button on the side and very affordable. These are often found with advertising on both sides and oddly sometimes advertising for different companies on the same knife. This one has BETZ COILS on the front and ALLIED SUPPLY CO, INC on the back. Blade is mostly full and stamped G SCHRADE over KNIFE CO INC, over B'PORT, CT USA on the front and Incorrect patent dates on the rear of 11-9-27 and 10-19-44. This patent wasn't applied for until around 1937. Many of these have the wrong dates for some reason. The knife is in VG condition with a white ball to pull to open the knife. Handles show wear and some shrinkage.