Yes, it goes by the narrowest part, which is the waist, so buy for that size and cut down.If you buy skins for the narrowest part of your skis you will have exposed base which sucks. The preferred method is buy skins for the width of your tip or in the Case of Volkl Mnatra 133m. 140mm skins would give you full coverage 120mm would leave about 6.5mm of base showing on each side of the ski at the wides part of the tip. If the side cut is aggressive you many not have much base exposed with 120mm.