Rain jackets should keep the rider dry. However, that's not always as easy as it sounds. If you want to wear a rain jacket for a longer time, it needs to be breathable; the last thing you want is to be soaked inside your jacket. Every manufacturer has its own way of providing breathability, for example with openings under the arms. Expensive jackets use membranes like GORE TEX, which are permanently waterproof and very breathable. An alternative is breathable polyurethane finished with a waterproof coating. Such jackets are usually more affordable, but can lose their waterproofness after time. With rain jackets, you should also look for an extended back, waterproof pockets and sealed zippers.