IN-17 is a cold cathode neon gas discharge indicator. Each tube is able to display the following shapes: '0 1 2 3 4 5 6 7 8 9'. There are normal "5" (not an upside down "2"). These are ones of the smallest tubes ever made. Digit size: approx 8 x 5.5 mm (H, W). Comes with a plastic socket.