Never wonder what size resistor to use again!
These are great for powering standard, 20mA LEDs. You can also put several LEDs in series and still maintain proper drive current. Another cool feature is that you can parallel these for higher current in multiples of 20mA (three would be 60mA).
Can be used pain-free, ABL LED color changes. Just put in series with each LED.
Overall length is 6" and wires are 24 AWG.