I originally ordered 40 of the GRV 921 T10 3528 12V leds from Amazon. They worked pretty good but not as bright as I wanted (they were the super bright warm white). After initial installation I began losing leds all the time. Many (10?) quit completely. Even more of them lost multiple leds. The inside of the camper now looks rather gloomy and yellow. A suggestion was made to me on this forum about having the 12V only leds vs the 12-28V models and I do think that is the problem. I have more than 12V at the bulb and in one of the sites for that led it said it could not have more than 12V or it would lead to led failure and burnout.
Ordered 20 of the GRV 921 T19 3528 12v-28v super bright cool white leds yesterday. Should have them Wednesday. I won't install for 2-3 weeks because we are out of state at one of our vacation homes. I'll try to update when I get them installed. The illustration of the cool white vs warm bright shows the cool white is considerably brighter. I hope they will be as bright as I hope; if not, I'll be ordering the 5050 leds which are supposed to be much brighter than the 3528.