These are 1-inch green LED 7-segment displays I picked up on eBay. I got 8 in total for a few dollars. I wanted to use up some off-cuts of stripboard so I ended up sticking 2 pieces together using epoxy glue and a strip of scrap ABS plastic which is on the back. The DIL socket will hold a MAX7219 integrated circuit when the display is finished. The MAX7219 is an intelligent driver which can handle binary-coded decimal as well as bit-addressed data. I'm going to play about with this and add it to the ever-growing box of 'modules' for the car computer project (if ever...) as it would make a great rev counter or speedometer, or both.