PAT INOX 19cm Spanish Silver bf OTF double action switchblade vintage

Vintage Spanish PAT INOX Silver bf 19cm OTF double action switchblade. The knife is very shiny silver and is NOT magnetic, so assuming it's painted/coated plastic on aluminum frame, but not sure. Never seen one of these before. It measures 18.5cm (7.25 inches) open. The saber grind spear blade appears to be full with factory finish and is marked PAT INOX. The bright silver handles have the letters "bf" raised above the release knob and a checker pattern on both sides. The knife works well with blade flying open when knob is pushed forward and closing when knob is pulled back. It does misfire sometimes, but you just pull the blade all the way open to reset it if that happens. This is an unusual Spanish OTF in EX++ condition.