Looks like a 1:1 copy of Fein 63502166210
I see Festool 204414 from your picture also still available (at least in NL). At a cost of about 50% more than the Fein.
EDIT: The Festool is listed as 1.2mm, the Fein 2.2mm
But seeing the photos... I think the Festool is 2.2 too.
EDIT 2; Might also try Bosch 2 608 900 034;
But this is 5mm less diameter and Starlock, not Starlock Plus. However, all Plus machines take this blade too.
Oh wait... you aren't looking for that blade, but the same in non-Starlock.
Afaik there is an adapter for Fein to use Starlock blades in the OS 400. Fein 35222952050