Mueller in the US makes decent probes and connectors. Not as nice as the German connectors but you know it will work out of the box.
Unfortunately, I have to dispute this statement: I ordered some Mueller BU-P1825 plugs (equivalent to Pomona 1825) and some were essentially useless. The ones that were fine (see red plug in attached photo) appear identical to the Pomona ones (4-sided banana plug), but others have a lantern-style plug that
looks like a Hirschmann or Stäubli, but doesn’t actually stay in when stacked! (Black plug in photo.)
Broadly speaking, American-style banana plugs — and crucially, the
sockets, too! — are shorter than European-style ones. Consequently, while an American plug will fit in a European socket fully, a European plug may not fit into an American socket all the way, causing some of it to remain exposed, but even worse (and this is the issue with the stackable lantern-style Mueller plugs), on some European-style lantern-type plugs, the “bulge” is actually far enough up the shaft of the pin that it won’t actually engage with a very shallow American socket.
So Mueller actually now sells a “stackable” plug that cannot stack with the same model…
(As in, if you took the black plug shown and pushed it into the back of the red one, it’d fall right out.)
Upshot is, I’ve never had to deal with this kind of nonsense with Hirschmann and Stäubli. Their plugs fit into everything and everything fits into their sockets.