5mm led, is the most popular dimension leds.
There is 5mm IR leds, 5mm blinking LEDs, 5mm blue leds, 5mm white leds, 5mm green leds, 5mm red leds, 5mm yellow leds, 5mm flat top leds, 5mm bullet leds, 5mm photo diodes, 5mm piranha leds, 5mm power leds, 5mm led dot matrix, 5mm bi-color led, 5mm rgb leds.