21 gallon tanks mean fewer refills and higher productivity compared to similar models. 3.5 hours of run-time on a single charge. Compact design allows it to be stored in the same closet as a walk-behind. Stainless steel chassis. Rear wheel drive system for ramp climbing ability up to 11%. Automatic pad loading system. Gel batteries are the safest, most dependable batteries on the market. Longest-life batteries on the market. Emit 1/40 of the hydrogen gas of wet lead acid batteries. Spill-proof and can be charged anywhere.