Here Calvin says "fitted with the latest Nichia NVSL219BT SW45 D220 LEDs, the successor to the popular NVSL219AT-H1 with lower VF and higher output." And over at The Bad Place he links to .pdf for NVSL219B-R85-E. I guess if you know the voltage bin for the old 219As you might could narrow down which applies to the 219B, I have tried to figure out the Nichia docs until my head hurts, and the best conclusion I can come to is that the Nichia folks hail from some strange parallel universe. (to be fair my head was hurting already before I started, but it's worse now)