If you're like me, Classic M6 owner, you hardly ever need to change batteries. But, if you're in Rome for a week you may find that you need them on day one. You can get them at a well supplied camera shop across from the Cancelleria, but the guy there won't be able to help you get battery cover off. He'll give you a card for a repair shop outside of town but you won't want to do that. What you might do is go to have a nice lunch in Campo de Fiori and spend an hour working your thumb and forefinger raw trying to get it off. You may fail. The two glasses of wine you will have will make the next part of the procedure much easier, emotionally. You will take the chrome end of your Cross pen, or equivalent, and with considerable force the cap will budge. Engage the chrome end with the knurled rim of the cap and begin to push carefully. You will worry about slipping and gouging the vulcanite. You will also worry about slipping and scratching the rangefinder window, or the top plate, so you will decide it's better to push toward the base plate. On the first try you will scrape off a few of the ridges and you will see the brass. You will remember that while the top plate is zinc this part and the base are still brass. You think, "well, I'll worry about this less in the future." Finally the cap comes off. Clean away the crud, in go the batteries, and all's right with the world again. Two weeks later the skin will begin to peel off of your thumb and forefinger. I just felt like sharing. Ciao.