These DOB "driver on board" leds are really cheap, but you get what you pay for. I've been using them for two years now and they work fine, but lm/W is really low ~80 and PPF/D PAR efficiency is half than other COBs, most of the electricity goes out as heat. If you don't mind the electricity bill and you can place many of them close to each other than you can grow fine with these. You will need at least twice the power compared to other COBs. I'm switching to OEM COBs like Bridgelux Vero SE series. They are cheap compared to CREE but you get so much more out of them compared to these DOBs.