Opening restrictors on Velux windows

[QueenBean]

Has anyone got any recommendations of these please? I have GHL windows which the velux produced ones don't fit.

I've seen some general window restrictors which can be applied to any door or window, but they're quite ugly thick white cables. I'd prefer a stainless steel thin bar.

Please let me know if you have used these and if so, where you got them from!