Automatic calculation of price plus tax, price less tax, discount, selling price, tax amount, discount amount, and margin amount. Two-way power Solar powered when light is sufficient, battery powered when light is insufficient. Key operations are stored in a buffer, so nothing is lost even during high-speed input. Extra Large display with 8 Digits Larger display makes more data easier to read.Plastic keys designed and engineered for easy operation. Durable metal Faceplate tough cover stands up to rough treatment.