Noticeably brighter than the factory bulbs (even with only 13k miles on the car). These are also more intensely red than the factory bulbs, which are white bulbs behind a red lens...they have a very orange-ish tint to them. These are a very deep red and catch the eye much better.Not to mention, for safety purposes, these illuminate noticeably faster than the incandescent factory bulbs. They snap on immediately and at full brightness. I replaced one bulb and had my wife pump the brakes repeatedly while I watched. Even in broad daylight, the difference was stark and distinctly in favor of these Philips bulbs for both brightness and their eye catching ability. I then, without telling my wife which bulb had been switched to LED, had her comment on them. She was able to immediately identify the Philips LED bulb. She, too, preferred it to the factory bulbs.This light is "all ate up" with heat sink mass, a VERY good thing. many aftermarket bulbs advertise tons of brightness. But, the primary enemy of any LED emitter is HEAT. Where is all that heat to go on those bigger aftermarket bulbs??? Especially if you were to say, GET STUCK IN A TRAFFIC JAM where your brake lights are lit continuously for an hour or more. Then what?I'll tell you what; those bulbs overheat or they have to reduce their brightness significantly (by as much as 80%). Overheating an LED can take a 50,000 hour emitter and turn it into a 50 hour emitter. I've done it. So, this bulb is brighter than factory, but not by a crazy amount. It's DOT road legal (nice if you get pulled over or you have annual state inspections). And it's going to work over the long haul.I'm very pleased. I think it's telling that Philips took so long to get into the MASSIVE aftermarket LED bulb game....maybe it took this long to truly get it right? Sure, there are brighter bulbs. Some as much as 2 to 3 times as bright as stock. But will they be THAT BRIGHT in a year? Two years? Five years? Ten years?These Philips bulbs have a very balanced design approach much like quality flashlights. Plenty of heat sink area and mass, they work WITH your factory bulb reflector (another issue entirely; where are all those fancy ultra-bright LED emitters AIMED?) to have the proper beam pattern at 200-500 feet behind your car, they were a perfect drop-in fit for my factory Nissan bulb sockets (not breaking the sockets as some aftermarket bulbs tend to do).Oh, and these draw much less electricity as compared to the factory bulbs. These eases the strain on my battery and alternator. With all the nav devices, stereos, bluetooth devices, and cell phone chargers in cars these days, reducing the electrical draw of your bulbs via LED replacements is a smart and effective way to get more life out of your battery...and MAYBE have a very slight positive effect on your MPG's due to lower load placed on your alternator. Regardless, it's more efficient, and I'm in favor of that.

The first LED "bulbs" in the 3157 format that actually can work legally and safely. Technically only a few vehicles have been tested, but I would bet most can pass. I've been running these since release back in October with no problems. I also have been running the 2-LED version of the 1157 with identical success.Some information to keep in mind:1. Ignore the marketing of this product. It's not as bad as Sylvania, but 5x light output is a pointless figure. Believe me though, when I say these are "5 millions times" better than every other LED on the market.2. These are not guaranteed to be legal for use or to work in every lamp ever produced.3. You should check Philips's website for tested cars.4. Before settling in with these, you should do some comparison checks of the light outputs yourself. Get a helper or an appropriate stick to hold the brake pedal. Then, find a clean wall (garage door may work), park your car a few feet away, and then check the output pattern and for any weak areas of light. Also, without a wall in your way, walk around your car at a few different distances & heights to check for weak areas. If you discover any areas that appear different from a standard 3157 bulb, or something just doesn't look right, these may not work safely for you. What I have noticed in my observations is a slight decrease in light output when looking pretty steeply down towards the lamp, something minimal enough that it probably doesn't effect legality or safety. I can also say that a Mark VIII high mount stop lamp doesn't cooperate well. This particular lamp already seemed weak considering it housed two 3457 bulbs, lighting both filaments, and still had poorer output than some dual 912 lamps or single 921 lamps. In general, I think larger tail/brake lamps are mostly going to work better.If everything seems okay, then...Pros:1: Probable legal light dispersion and outputs (notice the "s")2: Possible brightness improvements with older vehicles with teeny wires, but remember this is a 3157 designated bulb, therefore it is supposed to produce legal light outputs of a 3157 bulb.3: Instant on brakes and/or rear red turn signals4: Less load on weak electrical systems, especially in multi-bulb tail lamps, cars with weak alternators, and cars with every winter feature.Cons:1: Not necessarily plug and play. You will most likely need either an electronic flasher to replace your fixed load thermal flasher, or on a newer/fancier car may actually need load resister(s) or possibly a software flash or towing module setup. In the simplest adaptation, a flasher may set you back approximately $10, but as a beneficial side effect, may improve your flash consistency, speed, and start. ...and if you were really cheap, a variable load thermal (hazards) flasher might also work.