This Waterproof Plastic Mezuzah Case is a basic. It is made from one piece of plastic with a plastic plug on the bottom. It has a gold shin for decoration. Even though these cases are good for outdoor use and can withstand adverse weather conditions, I still recommend choosing the optional heat sealing of the klaf.
In my experience, the combination of starting with a waterproof case, and a heat-sealed klaf is what provides the best chance of a protected klaf over long term.
This waterproof plastic mezuzah case tends to turn yellow and become brittle when exposed to the sun for a number of years. However, it is quite inexpensive to replace and I recommend it for that reason.