ELEX 20cm Japanese vintage Lever swing guard jigged bone & brass automatic knife

ELEX 20cm Japanese vintage Lever swing guard jigged bone & brass automatic knife made in Japan in the 1950s or 60s. The knife measures 19.5cm (7 5/8 inches) open and 4 3/8 inches closed with steel liners and brass bolsters, guards, lever & pins. The saber clip blade is 95% full or better with patina, light scratches and a little spotting and is engraved ELEX on the face of the blade and PATENT over a series of numbers I can't make out. I can see "39090" I think. The only other marking on this knife is a "2" on the lever. The dyed jigged bone handles (scales) are dark and in excellent condition. The knife works well with blade tip deep when closed, good snap opens fully with excellent lockup. No rattle if shaken with blade open except the guards. VG+ condition.