Basically a 7 segment display is a single unit, which can display only 1 digit or 1 character . More digits are displayed by multiplexing single unit 7 segment displays together to form 2 digit display, 3 digit display or 4 digit 7 segment display. Its quiet easy to interface Arduino and 7 Segment display together! Product Name: LED Digital Display Tube; Type: Common Anode; Model: 3161BS Common Anode: 1-6; Digital Display: 1 Digit; Digital Number: 1 Bit 7 Segment; Emitted Color: Red Pin Number: 10; Continuous Forward Current: 20mA; Average Forward Voltage: 2V; Power Consumption: 36mW Luminous Intensity: 11mcd; Number Height: 0.35 inch; Panel Size: 14 x 7.5 x 8.5mm / 0.55″ x 0.3″ x 0.33″ (L*W*H); Total Size: 14 x 7.5 x 14mm / 0.55″ x 0.3″ x 0.55″ (L*W*H) Material: Plastic, Metal; Color: Black, White