Invented by Marcel Opinel in 1955, the Virobloc safety ring was improved in 2000 on all the Opinel ranges. Since that year it is possible to lock the blade in the closed position (safety during carrying). If you have a pre-2000 Opinel knife, this instructable will show you how to adjust the ring such that the blade can be locked when the knife is closed. It will only take 5 minutes. You need a iron saw and a bench vice.
Close the knife.
Put it in a bench vice.
Take your saw and saw a corner of the lower part of the safety ring. The cut starts just above top of the blade and ends at the same height as the cut ends that is on the upper part of the ring.
Move the ring over the closed blade.