Having a dual metric/inch tape is real handy here, for obvious reasons if your brain thinks in imperial. Funny thing is, nearly 200 years into the metric experiment in France, the inch (pouce) is still understood, you can buy potatoes in the market in livres ( pounds) and most plywood comes in 4' x 8' sheets, ( made in or for the US market). Had a laugh one day, saw a Brit strolling toward the builders' merchant office with a piece of unmistakable orange Brit pvc soil-pipe on his shoulder. UK = 110mm OD, 4" bore. French 100mm OD, 94mm bore, and totally incompatible. Hope he hadn't fitted too much already! One of my favorite things is to pretend to study a product, eavesdropping on some hapless Brit mangling the French language, (or just speaking English very loudly! ( "AVEZ-VOUS FOUR INCHES!!" ), while the long suffering assistant wishes he was someplace else, like on the beach in Cap d'Adge!