10 Standard Chess Clocks (up to 20 players)The Quartz clock is one of a kind, a battery powered analog clock. The contrasting black and white ensure a clear, readable display. There's no need to wind the Quartz since it operates on one AA battery. Easy to see and button tabs to prevent accidental dead batteries are two new features in this black colored Quartz. Functions the same as other basic chess clocks. Specifications: One AA battery required. Dimensions: 7 1 8" x 2 5 8" x 4 3 4"