36mm SMF4 LED (one)

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Availability: In stock

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36mm SMF4 is a direct replacement for any 34-38mm size halogen festoon bulb.
  • Warm White
  • Cool White (6000K)
  • Red
  • Blue
  • Amber
  • Green
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36mm SMF4 LED (one)

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36mm SMF4 is a direct replacement for any 34-38mm size halogen festoon bulb.

By changing the factory bulb to an LED, you can illuminate the area with a much brighter light, and add a pure white, luxury look.

The installation is 100% plug-and-play, just replace your factory bulb.



This bulb is a 36mm festoon bulb, but can fit in varying applications. It is made up of four SMDs mounted in the middle for OEM installation. You will not find a brighter LED bulb for this application! A load resistor is embedded to prevent blowing the LED from voltage surge, and a diode is implanted to protect the LED from reverse polarity. The LED is wired for 12V operation, the kind found on all vehicles.

Included in your order is ONE BULB.



These LEDs are available in crisp, bright colors including Cool White, Warm White, Blue, Red, Amber, and Green.

 We strongly recommend cool white or warm white for the best visibility.

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56 Lumens

Lumens: BUYER BEWARE! Most sellers just provide "calculated" lumen numbers, based on the maximum potential brightness of the LED chips on the bulb. For example, if a bulb has five 10-lumen chips, they will rate it at 50 lumens. However, this is not accurate, as the design of an LED bulb does not get rid of heat fast enough to run the LEDs at maximum.

These "calculated" lumen ratings are much, much higher than the true, measured light output, so it will look like competitors' bulbs are brighter than ours. This is because Diode Dynamics does not provide inflated "calculated" numbers; we believe it is misleading. We test the actual brightness of the bulbs in our lab, to provide real lumen output measurements. Our measurements are accurate, but they are usually much lower than the misleading "calculated" figures. Please click here to learn more about LED brightness measurement.



LED Components. Diode Dynamics uses only the highest quality LED chips in the production of its bulbs. This means we use only brand-name suppliers such as Epistar, Cree, Osram, and Samsung.

While our bulbs may look the same as others on the market, most copycat bulbs use economy-grade LED chips in order to reduce costs. This greatly reduces the reliability and overall brightness of the bulb when you compare it to Diode Dynamics.

Construction. Although LED technology allows for extremely long bulb life, the market is flooded with cheap LED bulbs that fail prematurely due to inferior construction. The worst enemy of LEDs is excessive heat, and when bulbs are not designed properly, they do not disperse heat as well, leading to premature failure.

Off-brand, cheap bulbs exhibit poor solder uniformity, high levels of flux in the solder, uneven chip placement, low-gauge terminal wires, poor assembly, and bulbs held together with inferior adhesives. At best, solder joints will crack and fail on low-quality LEDs after a few weeks of use. In the worst case, these bulbs can damage housings as the extra flux and adhesive evaporates and creates a residue on the lens of the housing.

Diode Dynamics bulbs are produced with modern, computerized equipment, and only the best materials, to ensure complete uniformity, high quality, and long bulb life.

All Diode Dynamics products come with a 30-day satisfaction guarantee and a 3-year limited replacement warranty. For more information, please view the FAQ guide.

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  1. Nice buy Review by Ron

    Ok to have for my dome light. I can see fine at night inside my car and having color white is better than boring yellow. Cheaper purchase than auto stores near by and I'd rather buy from diodedynamics anyway. (Posted on 2/7/17)

  2. Nice light, but..... Review by ysrpilot

    This was a great fit for my 2015 Hyundai Sonata glovebox light, but when inserting it into the holder be careful. Because of the design and the fact the holder was pretty stiff, the end of the bulb bent over. I bent it back, but it bent again. Not sure if it will hold up for long. The only thing keeping it rigid is two solder joints which aren't overly strong. I've used similar Diode Dynamics bulbs in less tight holders without issue. Not sure if it was a bulb issue or holder issue. Will ride it out for now. Guess I have three years to see if it breaks. I dropped one star for quality because it might be a bulb issue. (Posted on 9/28/15)

  3. AWESOME! Review by Rob

    I installed this 36mm 4-5050 SMD in my DOME light and couldn't be happier. Crisp white light emits through the entire interior! (Posted on 9/22/13)

  4. white light Review by Mike

    The stock trunk light in my car was so dim I had a hard time seeing what was in there at night, but not anymore. The bulb gives off a very clean, white light that makes it much easier to see what I have in the trunk. Very happy with this purchase. (Posted on 7/9/12)

  5. Bright Trunk LED bulb replacement Review by Steve

    I bought this festoon bulb for my Tiburon's trunk light and it gives off 80 lumens of bright white light that is alot brighter than the stock bulb...I am very happy with this bulbs light output for the money. (Posted on 12/23/11)

  6. Good, Could be better Review by Jhammer1228

    Had to do a little maneuvering to fit it into the fixture but got it to work and looks great, much better than my initial lighting! (Posted on 11/30/11)

  7. Not as bright as OEM 10W Festoon Review by Gerd

    Disappointed by the light output of the 36mm 4-5050 SMD. Bright white light, but not as bright as OEM 10W Festoon. If You are looking for a brighter replacement go for the 6 or 12 SMD Boards.

    Note from DD: This is our stage 1 replacement for the Subaru Forester. It is designed to be slightly less bright than stock, while still giving the LED look. Please feel free to exchange for a brighter bulb, and thanks for the review! (Posted on 11/26/11)

Worry-free warranty

  • -Full 3-year warranty on all products
  • -No waiting: we usually send new items out with a return label (US customers only)


You will get quick help from our trained staff for any issues.

All Stage Series products carry a limited 8-year warranty.

For further details, please see our full article.

Domestic (US) Customers

  • - Same-day shipping for all orders placed by 12:00 PM CST (or until 4 PM with rush processing)
  • - USPS, for delivery in 3-5 days (on average)
  • - Express services are available, see exact pricing at checkout
  • - Fully Insured


International Customers

  • - We ship to all countries via standard mail
  • - Usually around $10 for LEDs, or $25 for HIDs.
  • - Choose your service on checkout to see exact prices:
  • - USPS 1st Class: 2-5 weeks
  • - USPS Priority: 1-2 weeks
  • - Express EMS: 1 week
  • - Please email us if you are unsure about shipping to your country.

You will receive updates from our site when your order is shipped, along with a unique shipment number to ensure that your order is correctly accounted for. This allows you to easily reply to us if you have any concerns.

Whether your order is big or small, it is tested through many run cycles, and each bulb is tested before shipment. Every single bulb. Every time. And if anything does go wrong, you can rely on our industry-leading warranty for worry-free replacement.

If you're not happy with your items, we want to make it right. So we have some pretty awesome return policies:


30 day return policy. All customers have 30 days from the date of original order shipment to return items.

Full refund, no fees. At Diode Dynamics, we offer free returns. That means no restocking fees, no administrative fees, and no hassle!

 Free return label. If your original order was over $50, you get a free return label for your items (US customers only). If your order was less than $50 or international, you can send the items back through your preferred method.


Within 30 days: If your original order was over $50, you can get new items shipped to you with a return label (US customers only). If your order was less than $50 or international, we can send you the new items first, but you are responsible for returning the old items.

Within 90 days: Any item can be returned for exchange or store credit within 90 days. The buyer is responsible for the cost of the return shipping, and must first return the old items. We'll still cover the postage for the new items.


Please note: due to the nature of custom acrylic pieces, we cannot offer any refund or exchange for returned custom acrylic items.


To make a return or exchange, please request an RMA, or give us a call. When we get it back, you will be notified and credited appropriately.

Again, all returns must be approved, with an RMA. This is so that we can process your return as quickly as possible when we get it. If you would like to return an item, please Request an RMA. Please include as much information as possible about the reason for return.

Alternatively, you can also send us a message, or give us a call!