There are many options available to purchasers of central vac systems. Today's central vacuums are more powerful, quieter, and more hygienic than ever before -- far better than the best portable vacuum cleaners. However, in the field of built-in vacuum cleaners, how would you go about choosing the "best"? There are multiple manufacturers that make high-quality, premium equipment that we sell and recommend. But, if asked to choose a favorite, my choice has been the MD Central Vacuum. Their USA-made machines are fabricated of US Steel and powdercoated inside and out for durability even in the utilitarian areas where these units are typically installed. Unlike molded plastic housings, and those with single-stud mounting brackets, these units will not flex, distort, crack, or warp over decades of use. The exclusive triple intakes (left or right piping connection, plus center metal gasketed utility inlet) allow for easy and clean hookups without a "rollercoaster ride" or "spaghetti mess" of pipes such as single-intake or split-canister machines often have. The triple layered filtration system starts with the 8-gallon disposable Tru-Seal patented filter bag, which seals in many months' worth of vacuumed debris for clean emptying. This bag is augmented by the permanent cloth bag, which not only acts as a second layer of filtration, but also supports the disposable bag, enabling maximum airflow across the bag's entire surface area. This means full cleaning power for an extended period of time, and more economical operation. Beyond the permanent cloth support bag is a final mesh pad filter protecting the motor from debris in case of a failure or improper installation of the primary filters. Integrated into the MD Flo-Master is an air relief valve, which protects the machine in case of a blockage in the hose or piping. This valve opens to allow air to flow directly to the motor and cool it, and automatically resets when the blockage condition is removed. In addition to this safety valve are integrated thermal and overcurrent protectors. The unit can be exhausted to the outdoors, but we only recommend this if the machine is in a confined area or if odor control from vacuumed debris is a concern. The exhaust is clean, and thus can otherwise freely discharge into the area where the machine is located. "You can't beat a built-in vacuum" -- especially an MD Flo-Master!