It took some effort to finally determine that I needed 3 watt LED's. I initially tested every LED in the grow light using a diode tester on my voltmeter. If good, the lights would illuminate. To insure that the light would work again, I jumpered out the faulty lights to insure that I could make the lights come on. On my grow lights there were four banks of 13 lights. Any defective light in a bank would kill the whole bank. It was difficult to get the bad light off. I am no expert on surface mounted components. I had to apply a lot of heat to get the old led to release from the board. These new lights went on fairly easy. It's important to use heat transfer cement on the diodes or they will not last very long. When done, all the lights were burning brightly.Exactly what i needed! Easy to work with.Perfect to fit clients grow lightI liked everything except one thing. That is the plus sine is hard to read on the little metal tab but it’s there just have to look closely.