Found in the Rouen flea market. It's 4 1/2" (20.5 cm) in length.
The brand "Prefer" has an English spelling (Only two e's, and no accent marks over them). The accents, grave and acute, can be seen over the appropriate 3 of the four e's in the the words "Modele Depose" (tr. patented) on the flip side of the this wrench. This bicycle wrench must have been intended for the English market as well as the French market.
The wrench itself is nicely made from thick stock. The adjusting wheel is steel, as is the wrench. I judge the wrench to be from the period between 1890 and 1910.