The main driver for Outdoor use is material, followed by color options. Both Aluminum and Stainless Steel can be made Weatherproof or Weather Resistant, while Plastic is always ready for Outdoor conditions. The Economy line materials can be made Weather Resistant, which means they can stand up to wet conditions but are susceptible to rusting over long periods of exposure. However, the Premium line materials can be made Weatherproof which is rust resistant for extended Outdoor use. Base material also plays an important role. Outdoor models come with either an ABS base, typically in black, or Recycled Rubber that can either be solid or fillable with sand, water, or other such materials for stability. These bases can be used indoors as well, however many of our indoor models come with matching material bases such as polished Aluminum or Steel.