This is a set of 10 L.E.D.bulbs. They are 12 volt 3 mm, 3500 MCD L.E.D bulbs that can be used in Delco radios like the one’s pictured below. They will dim with the dimmer switch. They do not require resistors to convert them to 12 volts. You can also use them in climate control switches, door lock switches, power window switches and even in instrument clusters. They come in 4 different colors at this time. They are Red, Green, Blue, and Cool White. I have installed all of the colors. But when I installed the cool white bulbs they look bluish to me.