Of the cleaners tested, this is the only one that consistently picked up dimes and pennies on the bottom of the swimming pool. This self-propelled robotic pool cleaner was chosen Best in a study by the Hammacher Schlemmer Institute and is also manufactured by the preferred pool company for international swim meet competitions. Over a two-day period, pool cleaners were used to remove sand, leaves, twigs and coins that were added to a public swimming pool to test vacuuming ability. The Best cleaner has a 24-volt DC motor and is capable of climbing walls and scrubbing across the water line. In addition to this superior vacuuming ability, it was also selected for the ease with which it could be used. The vacuum set-up requires only that the user place the cleaner in the pool; it sinks to the bottom and automatically programs itself, diagramming the most efficient cleaning pattern for total pool coverage. This unit also scored high when evaluated for its ease of removing debris. In just one crossing of the pool's surface, it successfully vacuumed up all foreign objects in its immediate path. One-piece filter cartridge rinses clean with a garden hose. For above ground or in-ground, residential pools. Average pool cleaning time ranges from 2 to 3 hours. Automatic shut-off after 5 hours. 11" H x 15" W x 16" L.