In the U.S., we always used the R-5, and our mechanic drilled them for us. I think these read ZIMAR? These have the little copper-contact on the flat side.
In Seville, we purchased a Tecnomar 125mm (same size as the R-5) and we had a diver install a pair in Italy a couple of months ago. It seems to be abrading at about the same speed as the R-5, so it looks like it will last about a year.
The Tecnomar does not have the copper contact! Should I be concerned?
SM2K No. 350 (2002)
At anchor, Salerno