Features Direct replacement for factory 28mm festoon bulb Adds more modern LED appearance Plug and play simple installation Overview Design. The 28mm SMF1 LED bulb is a direct replacement for any 28mm-size bulb commonly found in vanity mirror lights in many vehicles. Populated with one 5050-size SMD the SMF1 upgrades the factory yellowish incandescent bulb to a more modern LED appearance. The SMF1 was designed with an embedded load resistor and implanted diode for superior reliability. With its durable metal terminals it will fit snugly in the socket and its light weight means it won't vibrate loose over time. Reliability. Unlike other bulbs on the market this bulb is built with constant-current circuitry along with transient suppression. That means this bulb will last for years not months with no flickering or failure. And like every Diode Dynamics product it's backed by an industry-leading three-year replacement warranty. Brightness. With 16 lumens of true measured output the SMF1 LED will provide similar light output to your original 28mm-sized bulb. If you are looking to increase output we'd recommend checking out our SMF2 option! All Diode Dynamics LED lighting is rated with accurate measured lumen figures not calculations or guesses. We test the true output in-house and provide you the real numbers to compare. Colors. In addition to vibrant colors of blue red amber and green the SMF1 is available in a cool white 6000K and warm white 3000K option as well. Whether you want a modern cool white appearance or a traditional warm white color we have the color to fit your need!