Bright, but expensive.
These bulbs are brighter and whiter than a stock bulb, especially in a projector type headlight. After hitting a deer because the stock bulbs didn't show the deer standing in the middle of the road until too late, i switched to these. I hope the price includes long life use, when a stock bulb is only 7-9 dollars.

Not so blue but bright for sure.
Had them for several days. If you are looking for something that is "blue", click return and go for other products. I used to have IPF(very good brand btw but you can hardly find it in the US) H4 on another car which was 4000K and it looked bluer than the PIAA.

But if you are looking for a better vision at night, this bulb is great!! I had some other brand that looks blue (4350K) but no way does the vision at night match the PIAA.

I prefer brighter vision at night so that I just stored my old bulbs and use PIAA.

I gave it a 4 because of the same reason the other guy had - I did not have it long enough so I can not judge its durability.

Bulbs Suck
I have no idea how the previous owner thinks these bulbs are white...the light is CLEARLY YELLOW! my stock bulbs are better than these. The color tempreature with a meter was about 2900Kelvin NOT EVEN CLOSE to the 4000K advertised... did i get the wrong item? Packaging said 4000K XTREME PLUS!

Caution this is NOT Xtreme White
I bought it because I thought PIAA is a famous brand. But returned the item right away after finding out that it is no way close to Xtreme White. It says 4000K but but I think it is close to 3600K. Not only that it wasn't powerful enough as well.

H11 is very unique fitting and it is hard to find in local dealers because only few vehicles use it. Like my 2006 4Runner. So you dont have much options. But recently all the big brands have released this fitting which can be easily found on internet (after a few searches).

Finally I bought H11 NOKYA 4500K with high watt output. I am really happy with it.

A noticable difference
These bulbs provide a noticeable difference is lumen output. To compare the light output to the factory bulbs, I only installed one of the bulbs and aimed the headlights at my garage door at night. I don't have access to a light meter but the difference was obvious.

Also, the color temperature of these bulbs is a pleasant white with a hint of blue.

I gave the bulbs 4 stars because I've only had them for two weeks and I'm not sure of the bulb's longevity.