In reply to Jacob-Oconnor: Your plastics are likely to be noticeably bigger than leathers of the same size. They may just not fit. I have a pair of yetis (actually Extremities) that go on my Nepal Extremies, and then another bigger pair that go on my Vegas. For day climbs I don't think you really need yetis on plastics, but if you are camping in deep snow for a long time they are helpful at keeping snow out of the boot.