Ewa matte box questions

[Yemi]

Do any of you own the Ewa S8K matte box kit? I hear that it can be adapted
to
support an anamorphic on many popular camera models. By what means is the
anamorphic lens held in place by the Ewa support? Does the anamorphic need
to be threaded or is simply clamped into place? Can it hold a range of
sizes? How sturdy is it?

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Yemi