NEW PRODUCTS! Green, Red and Yellow 7-segment clock displays – 0.39″ digit height! Design a clock, timer or counter into your next project using our pretty 4-digit seven-segment display. These bright crisp displays are good for adding numeric output. Besides the four 7-segments, there are decimal points on each digit and an extra wire for colon-dots in the center (good for time-based projects) and a top right hand dot which could be used to indicated a ° (degree) symbol for temperature feedback.
These displays are multiplexed, common-cathode. What that means it that you can use a 74HC595 or just 8 microcontroller pins if you can spare them to control the 8 anodes (7-seg + decimal) at about ~15mA each, and then connect NPN transistors or a TPIC6B595 to the cathodes to sink the 8*20mA = ~120mA maximum per digit.
Dimensions: 0.508″ x 1.582″ (12.84mm x 40.19mm)
The datasheet has lots more information on BL-Q39A-42UHR-11