Isoflux membrane developed by Sherwood Forest is highly efficient waterproof and breathable membrane. Isoflux is designed for complete protection from the elements. It is specially constructed using fully breathable fabric which has been treated in order to make it wholly impervious to water.

This then ensures your comfort and security from the elements at all times allowing you, the wearer to stay warm whilst minimising perspiration even in the most extreme circumstances.

Hydrostatic Head

Hydrostatic Head – this is how water resistant the garment material is. It measures how tall a column of water that the fabric can hold before water starts to seep through the garment.

A hydrostatic head of 5000mm means that the garment can hold a column of water that is 5000mm tall.

Waterproof Ratings

The table below shows you how waterproof a garment will be. The higher the waterproof rating, the longer the fabric will remain waterproof for.




0 – 1.500mm

Water resistant / shower proof

Light rain

1.500mm – 5.000mm


Light to average rain


Very waterproof

Moderate to heavy rain


Highly waterproof

Heavy rain

Most of our jackets offer a 3-layer system. Our three-layer waterproof jackets contain an external water repellent coated fabric, an internal Isoflux waterproof and breathable membrane and an additional protective lining.

MVP – Breathability

Breathability rating – this is the second number after the waterproof rating, this indicates how breathable the garment is. The number is expressed in grams, it represents how much vapour can move through one square meter of fabric from inside out in a 24-hour period.

Up to 10mvp is adequate for the average person who are not breaking a sweat by doing excessive activities.

Garments between 10 & 15mvp are well suited for the more active person or someone who will be wearing the garments for a much longer period of time.