In reply to JohnBson:
The Teodul Glacier - from when you leave Testa Grigia till you get to the Klein Matterhorn (or rather cross the T bar lift a couple of hundred metres from KM) You are on pisted ski pistes with no crevasse problem whatever. You then join the well beaten track up the Breithorn until you get to the Breithornpass. It's after that, traversing along under the S side of the Breithorn, that there will be crevasse danger.