Citizen GEN6 COBs are the latest generation of Citizen COBs They offer improved flux and thermal dissipation over GEN5, and can operate up to an amazing 120C case temperature.
CLU-1216 is a nominal 36V COB which has 4 more strings of dies than a 1212 and thus operates at higher efficiency and lower voltage. It is the best chip Citizen offers in a 36V package. 1216 can operate up to 3.68A max (approximately 155W) with proper cooling. Best efficiency is seen below 75W with this chip. As you can see from the chart below, the 1216 is below 35V at 1400 mA or less, which allows for a better fit on drivers in some cases
90CRI offers an enhanced red spectrum with the red peak centered around 625 nm
Tech specs on the COBs are found on the 1216 datasheet here