Klättermusen MFR
The Mass Flow Resistance System

Very limited wind resistance

Very limited wind resistance

Klättermusen’s MFR system helps you decide which equipment to select for your next adventure. The system will assist you in determining what equipment to bring no matter the activity or weather.

Modern outdoor equipment uses a wealth of different materials with varying characteristics. Air permeability is an important characteristic that Klättermusen considers when constructing equipment for maximum resistance to external conditions. The MFR system was created to put our equipment’s air permeability into a larger framework where the key is keeping you warm and dry.

Mass Flow

The concept Mass Flow is a technical description of how easily a gas, in this case air, passes through a fabric.


The Resistance in a fabric determines both how much the surrounding air will cool you, as well as how efficiently moisture generated by your body will be transported away. The higher the resistance the more air will be trapped and keep you warm, but moisture will escape with less efficiency.


For mountaineers deciding which equipment to pack is dependent on external conditions and the technical aspects of the ascent. Bringing everything is rarely a realistic option, that is why we have put our equipment into a system. By combining equipment with different MFR values you can adapt your equipment selection to the adventure at hand.