David from Mountain Warehouse explains and demonstrates the Hydrostatic Head Test with various squares of Mountain Warehouse fabric, to help you better understand our waterproof ratings!
Check out our waterproof range here: http://www.mountainwarehouse.com/mens/jackets/mens-waterproof-jackets/
and here
http://www.mountainwarehouse.com/womens/jackets/womens-waterproof-jackets/
