Round peg for a square hole
When it comes to replacing an obsolete battery in a vintage device, you pretty much have to take what you can get. Fortunately in this case, what I got was pretty good. The battery measured 16 volts on the analog multimeter (Micronta 22-205) in which I installed it (a function that does not require an internal battery) and it fit in the battery slot just fine, despite being a different shape and size. The original Mallory 504 battery was square and a slight bit longer than this replacement, which is cylindrical and a hair shorter. Despite these differences, it seems to fit snugly. If it slips over time, I can always either tape or wedge it into place. The bottom line is the meter is now fully functional on all its ranges. I only just finished installing this alkaline battery so time will tell regarding its longevity but I do believe the manufacturer's claim of a longer life than the original carbon zinc battery is likely valid.
Verified purchase: YesCondition: New