Sir you just took me back to 1967 o a country fair in the east of England ,I was 12 yo with 5 or 6 mates and we all bought a knife with that open system but in a 4 inch German cat knife style .I know 1 buddy who still has his 56 years later .I have collected knives all my life and never seen another until your video.,Even when from 1995 until into the 2000s I holidayed and stayed with friends in Portland Oregon and scoured the vintage shops up and down the Pacific coast buying every Italian switch blade (illegal in the uk like anything sharper than a crayon) a 1979 case jigged wood large hunter (as John Wayne used in Rooster Cogburn) $2 to the £1 and ran up my credit card up until it screamed .Happy days thanks for reminding an old man of days of yore .