If anyone is headed to Unicell, I'd recommend being careful and checking that the batteries that you are paying for are exactly what the packaging claims to be. I got a PX27 for a Rollei 35, and gee, was indicated on the packaging that it was a mercury cell. Took it apart at home, and they are LR44s x 4. Its not a one-off btw, I bought 3 PX27s. All the same.
Have not bothered to head down to find out exactly why the hell they would do something like that.
rf