Molecular Sieves are the expensive beasts you need for extreme heat or when you need practically zero humidity. Activated Clay is the cheap option that works great for bulk stuff provided it doesn’t get hotter than 50°C. Silica Gel is the versatile all rounderEveryone knows Silica Gel. While Silica Gel slowly sips moisture, Molecular Sieves grab it violently. Even if the relative humidity (RH) is below 10%, Molecular Sieves will still hunt down water molecules and trap them.