In what way is this jacket waterproof?
Waterproofing is tested according to JIS 1092. In this regard, the fabric undergoes water pressure measured as a column of water in mm: the higher it is, the better! What this actually means is 5,000 mm (Schmerbers) is the equivalent to 1 hour of protection in showers. Performance before washing certified.
Why wear a windproof jacket?
A waterproof fabric is also windproof. The coating that blocks the water also stops air currents. A vital factor in hiking as this wind considerably amplifies the feeling of cold, whether this is while you are exercising or at rest.
A jacket that breathes, what’s the purpose of this?
Thermal Evaporative Resistance (RET) indicates how the fabric allows body moisture to escape. The lower it is, the better! At RET=12, the jacket effectively wicks away perspiration. Scale: <6 = extremely breathable, <12 = highly breathable, <20 = breathable, >20 = not very breathable.