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Posted by Bethan Bithell on Jul 05, 2015

When buying outdoor clothing or equipment, you may come across the term ‘Hydrostatic Head’. This term refers to how waterproof the fabric is.

Hydrostatic Head Measurement

If an outdoor jacket has a Hydrostatic Head (HH) measurement of 5000mm, this means the fabric can hold 5000mm of water in a column before it starts to leak.

Therefore the higher the value, the more water and water pressure the fabric can hold before the water comes through.

As a rule of thumb, a basic waterproof outdoor jacket has a 3000mm HH value. At this value the fabric is classed as waterproof.

Therefore, if you are looking for a jacket that is highly waterproof and will withstand heavier downpours and extreme conditions, a higher value HH is needed, such as a Hydrostatic Head value of 5000mm.

An example of a shooting jacket that has a HH value of 5000mm is the Highlander Rexmoor Camouflage jacket.