OSRAM LEDriving® SL, ≜ P21W, White 6000K, LED signal lamps, Off-road only, non ECE, Double Blister

They have a similar brightness level to standard halogen bulbs while looking more modern, and should hopefully last much longer. One minor issue though is that they didn't work at first, until I used a screwdriver to bend the metal contacts in the bulb holder to make a better connection. They've worked flawlessly since. My car doesn't have CANBUS detection so I don't have to worry about that, but looking at other reviews it seems they would trigger errors if it did.

The Osram W21/5W LED bulbs are excellent! They provide bright and clear light, significantly improving visibility. Easy to install, energy-efficient, and long-lasting, they’re a perfect upgrade from standard bulbs. Highly recommended for anyone looking to enhance their car’s lighting.

Same size as the bulbs it replace a 1000% brighter.

I'm at a loss to understand how these can be quite so bad. I have bought a lot of Osram bulbs and they're generally great quality. Something seriously amiss with these ones however. The 5W "tail" performance is shown in the photos. You'll see I took the bulbs out of the fitting for one photo as when in the fitting it looked like it's not actually lit.The comparison pic shows the normal incandescents on the left and the LEDs on the right. These were taken on the same manual camera settings. Both are much brighter than in reality. I could have adjusted to look more like reality, but I didn't want to alter the photos. So although the incandescents look just a bit brighter, in practice the difference is much greater as shown by the shot with one of each bulb type in the same light fitting (incandescent left, LED right).The other issue is that the 21W circuit (i.e. the "stop"/brake light part) was very intermittent. This was due to the bulb base being slimmer than a standard incandescent. They're basicaly a bit loose in the fitting and the brake light circuit contact was not intermittent. It might be possible (although not easy) to bend out the bulb holder contacts a bitto make them a more snug fit, but I didn't want to risk breaking the bulb holders and it shouldn't be necessary.They may be OK in some applications and it's possible other bulb holders might suit them better, but I can't recommend for a stop and tail light. I was looking for a brighter light and faster reaction for the brake light. While it does light faster (when I can get it to light at all), both the tail light and the brake light are dimmer than incandescents and so plain dangerous.

First things first, the "Off-road only, non ECE" marking is crucial here for UK users. This means it's not legal for use as an exterior light on your car if it's going to be driven on public roads (e.g., number plate lights, exterior signal lamps). For interior lights, like courtesy lights, map lights, or boot lights, it's generally fine and can make a big difference.The light output from this OSRAM LED is noticeably brighter and much whiter than the standard filament C5W bulb it replaced. The 6000K colour temperature gives that very modern, crisp, almost slightly blue-ish white light. It certainly updates the look of the car's interior when the light comes on.Installation was straightforward – it's a direct replacement for a standard 36mm festoon bulb, just pop the old one out and put this one in. Being LED, it should also have a much longer lifespan than a traditional bulb and consume less power, though for an interior light that's on infrequently, that's less of a major concern.OSRAM is a well-known brand, and the bulb feels reasonably well-made for what it is.Pros:Significantly Brighter Than Standard Bulb: Provides a much more intense light output.Crisp, Modern White Light (6000K): Gives a clean, contemporary look to interior lighting.Easy to Install: Direct replacement for a standard C5W 36mm festoon bulb – plug and play.Reputable Brand (OSRAM): Generally associated with good quality lighting products.Low Power Consumption & Potentially Long Life: Typical benefits of LED technology.Cons:STRICTLY OFF-ROAD/INTERIOR USE ONLY (Non ECE Approved): This is the biggest point for UK users. It is NOT legal for exterior road use (like number plate lights or indicators, if it were an indicator bulb type) as it lacks ECE approval. Using it externally could lead to MOT failure or issues with the police.Can Be Very Bright/Clinical: The 6000K light is very white and bright, which some might find a bit too harsh or "clinical" for an interior, preferring a warmer tone.Potential for CANbus Errors (if used in monitored circuits): While less common for simple interior festoon bulbs, if used in a circuit that is monitored by the car's CANbus system (more likely if someone were to try and use it externally against advice), it could throw up a bulb failure warning due to the lower power draw of the LED. This particular C5W is less likely to cause this internally, but it's a general LED retrofit consideration.Single Blister Pack: You only get one lamp, so if you need to replace a pair, you'll need to buy two.Directional Light: LEDs are typically more directional than filament bulbs. Depending on the housing, this might lead to uneven light spread if the LED isn't positioned optimally within the light fitting, though for a festoon, it's usually less of an issue.Overall:As a replacement for an interior C5W festoon bulb in my car, this OSRAM LEDriving SL has done a great job of modernising the look with its bright, crisp 6000K white light. It's noticeably brighter and makes the interior feel a bit more premium when it illuminates.However, the "Off-road only, non ECE" status cannot be stressed enough for UK buyers. Do not use this for your number plate lights or any other exterior application if you intend to drive the car on public roads. For interior upgrades like courtesy lights, boot lights, or glove box lights where ECE approval isn't a factor, it's a good quality option from a known brand. Just be sure the cool white 6000K light is to your taste.

Took a chance on these as nowhere in sales description is canbus mentioned... but pleasantly surprised to see on back of packaging it says Canbus compatible... and they are.. well for a Volvo C30 anyway. The bulbs are very nice. Not too bright (photo exaggerates effect) and a classy upgrade thats looks pretty much OEM. So pleased with these am now going to try the Osram 21w led version for my reversing lights which need an upgrade. Hoping they last as long as Osram say.

Technically perfect, CANBUS compatible so no errors on dash. However not greatest for my use scenario - I have used them for wing mirror indicators in Volvo V70 III and it is not the brightest I have to say.Light looks more focused and not dissolved through reflective surfaces of the indicator, which kinda makes sense with them being LED.