We carry the stainless and the plastic Berkey filter units. All use the same filters so have the same quality of water. the plastic body unit is called the light. It is a good choice for a portable unit as it will withstand being dropped or etc better then the stainless. The stainless looks nicer and has more models. Although the "Big Berkey" is the famous model, it may not be the best for you. The only difference from one stainless model to the next is how much water it holds. The smallest in the series is the travel Berkey, which is a 1.5 gallon capacity, the "Big" is 2.25 gal, "Royal" is 3.25gal, "Imperial" is 5.5gal, "Crown" is 6 gal. The Light is 2.75 gallons. The sport bottle uses the same filter technology downsized to fit in the bottle. We do recommend it.For more information e-mail us or visit the informational section of the site www.omahaknife.com ***Many people buy these units as emergency preparation. We encourage you to use it from day one because your tap water isn't very clean plus assures you have a good unit and know how to set it up. add extra filters to your emergency supplies.*** Note- Read the directions for priming the filters. This is one of those few times printed directions do matter.***