The Supernova E3 PURE 3 and AIRSTREAM TAIL LIGHT 2 are high quality, very well built lights.

But with the quick evolution of the LED technology, they are now outdated in light power.

My Birdy 3 that was in stock at a R&M dealer, was from factory equipped with the SP hub dynamo and the E3 PURE 3 + AIRSTREAM TAIL LIGHT 2, it wasn't a real choice of mine.

Both lights turn on immediately as soon as the front wheel turns and there is a long stand-light on both. Its provided from the front light, the rear light has no builtin supercap or anything to provide a stand-light.

From what I understand, the rear light output of the Supernova dynamo front light is DC, not AC as for all other dynamo front and rear lights, and the AIRSTREAM TAIL LIGHT 2 works with a DC input.