Been using the rechargeables since last summer (same set), with weekly use on my F-75. This is a public service message to encourage folks to use rechargeables if they can. I've saved a lot of money by using these and in the long run, fewer batteries end up in the landfill. Last week's finds with the F-75, including a 1911-S semi-key wheat, a 1920 and 1942 merc, a 1906 Injun, a copper compact, and a silver ring from the turf that was down at the 1940s depth stratum (7-8 inches). Thanks for looking. - Jim