The GripGrab RaceAqua is a lightweight, waterproof and aerodynamic overshoe that protects against wind and rain. The stretchable waterproof material has a snug fit, and a zipper on the back ensures it's easy to put on. The RaceAqua shoe covers will keep your feet dry longer than normal overshoes. The RaceAqua was the 'best overshoe' in an extensive test, done by Fiets magazine in 2013.
Bear in mind that waterproof overshoes can still lead to wet feet. This is due to water finding its way in through the soles of your cycling shoes or by running down into the shoes from your legs.
For road shoes, order one size up from what the sizing table recommends. So if you're a size 45, order the overshoes suitable for size 46. For MTB shoes, order 2 sizes up from what the sizing table recommends. So if you're a size 44, order the overshoes suitable for size 46.