These are becoming quite rare - Simplex SLJ, sometimes badget Huret or Galli (have these) or even Mavic, they were considered an upgrade from Campaq ones as there was less issues with slipping etc.
Lots of pros used them in the 70s on otherwise full Campagnolo bikes. Their retrofriction design was easier to shift. Campagnolo copied it but only made a few and they are very rare.
These are becoming quite rare - Simplex SLJ, sometimes badget Huret or Galli (have these) or even Mavic, they were considered an upgrade from Campaq ones as there was less issues with slipping etc.
Nice bike, so BUMP and GLWS