I would not try the SR atty on a
device that is over 5 volts. Until you can verify the ohm on the SR, It keep the
device at 5. For the LR, 4 max. Multimeters are the best tool to check. Takes a few seconds to check and you know for sure. I check all my new attys as they come in. So I know they good. And I check again after I clean them. Your guess is right SR is Standard probably 2.8, LR is low rez 1.5-2.2 i think