4" 7-segment displays have several LEDs in series per segment. Usually four.
Vf (working voltage) of four LEDs can be 8volt or more, depending on LED colour.
Easy to drive them with a TPIC shift register.
TPIC6B595 (ebay) if you build it yourself.
Sparkfun uses the TPIC6C596 on these boards.
Leo..