Seiwa 3mm superbright green LEDs

These are water clear 3mm LEDs that light up a very bright green. Brightness ratings are unknown as a datasheet isn't available, but they would be at least 3000mcd at a beam angle of 45 degrees. 20mA maximum continuous current and Vf is around 3.2V. The output beam is a very nice and even diffuse beam.

High quality LEDs from Seiwa Electric in Japan. Part number SDPG3DD0A1000.

Note: these LEDs have their own tiny reverse polarity protection clamping diode built in, you can't connect them in reverse parallel with other LEDs as they clamp their reverse voltage to around 1.4V. Of course, using them as a normal LED in forward bias, they work like any regular 525nm green LED.