From the FAQ thread: /ubbthreads/images/graemlins/smile.gif
The Arc-AA is available in one grade: Standard with a SB2 Nichia LED.
The Arc-AAA use a 5mm Nichia LED part number NSPW500BS. Like all good LEDs, Nichia bins these LEDs by tint and flux. The Standard Arc-AAA uses a R or S flux and B2 or B3 tint. The Premium Arc-AAA uses a S flux with a B2 or B1 tint. The difference between the Standard and Premium is the Premium will have a warmer tint. All white LEDs tend to have a blue center and the Premiums are no exception. The difference is the Premiums will have less blue than the standards. The S flux is rated at 6400mcd at the factory but we overdrive the LED at approximately 45mA to produce about 20,000mcd.