The true Quebec darkfield principle is used with this counter. When in contrast against the darkfield background, bacteria colonies are bright and can be distinguished quite easily from other structures in the agar. Round dishes up to 100 mm in diameter may be centered because the dish holder is adjustable. Case is 10"" x 11"" x 10.5"". Counter comes with a 40-watt lamp, a tilt leg that may be adjusted to provide the most convenient viewing angle, and a white ruled Wolffhuegel guide plate. For 115 volt, 60 Hz. Warranty: 2 years. CSA Approved.