First of all we remuve the lens we want to change pulling firmly the upper part of the frame (keeping steady the nose part with the other hand) to unlock the lens from the two upper joins, then we can unlock the bottom joins simply by pulling the frame on the outside part of every join.

We know take the other lens and we insert for first the nose part in the predisposed slot, one side first and then the other one, in a way that the grooves of the lens can be locked in the housings in the slot in the frame.It' s really important, before passing over, to be sure that the nose is assured to the frame.

When the nose part is assured , we can lock the slots in the housings in frame in this order: the two ones on the sides, one on each side, then the two ones on the top.

In order to avoid to make the lens dirty during the change, we suggest to use the microfiber bag like a glove.