Engineered waterproofingmeasured in mm of water that can be held by the fabric without leaking 1 000mm is the minimum measurement needed to pass the accepted definition of waterproof for a garment to be truly waterproof the seams must be sealed in addition to the fabric itself being waterproof all endura waterproof garments are 100 seam sealed breathabilitymeasured in grams of moisture that can pass through a square metre of fabric over 24hrs gm224hrs using the b 1 inverted cup met