For me it was OK for Spirella

They fitted for me. I have already hung at least 3 shower curtains from Spirella and also those from another brand on this system.

I only have a kind of Spirella shower curtain and it works.

As far as I know, this track system works with all Spirella shower curtain grommets. I have been using this system for many years and I am very satisfied with it. You have to be careful to fix the curtain gently enough not to damage one of the 4 points of the "slider".