3mm LEDS are some of the smallest through-hole LEDS available. They are generally used for backlighting purposes and for general status indicator lights. Some of the benefits of using 3mm LEDS are the low power consumption, the long life of LEDS, their small size and their high level of reliability. 3mm LEDS are available in a variety shapes, but the typical dome or bullet shape is the most common. Look for red, green, blue, yellow, amber or orange, and white LEDS as standard offerings.