The HID lights on my 2006 Toyota Prius had become so dim that it was dangerous. I was always overdriving my headlights and there was no visible change in output from low beam to high beam. It seemed that some owners had positive things to say about Alla Lighting so I purchased their "PK32d Base D1S D2S D3S D4S HID Change to LED, Xenon White".
Alla links to a YouTube video from their product page that is very detailed in how to remove the headlight assembly and accomplish the required ballast bypass and wiring.
The hardest part of the job, for me, was removing the dust cover from the lamp compartment. After 19 years, the dust cover just would not rotate for removal. It took me about 40 minutes of trying to turn it with hand force, strap wrenches, mallet-tapping (and much swearing). I tried to turn it slightly both ways in turn, to see if I could break the adhesion of the o-ring which seemed to be absolutely welded to the cover and body. Finally I put a large adjustable box wrench on the square wire housing and rocked it back and forth until FINALLY, it began to turn. The crazy thing is the second headlight dust cover came right off by hand. So plan for the worst and hope for the best. On reassembly, I sprayed some silicone on a paper towel and then wiped the o-ring to make it easier in the future.
The video directs you to install the LED bulb so that the two LED elements are vertical in the housing. That doesn't work for this bulb because there is only one LED element, and the housing is keyed and the bulb base is detented with a ball bearing so it would only install with the one LED element facing up and horizontal.
The bulb assembly is a two-wire with a small electronics box in line. The connections are a small spade for negative and a slightly larger spade for positive 12V. There is an attached label that specifies polarity, which is at variance with the video (which says polarity doesn't matter). So I kept red-red and black-black.
The video suggests that you tap into the 12V two wires running to the old ballast. In my case, I pulled the 12V connector from the old ballast because I wanted to not power it since it was being bypassed anyway. When I examined that connector I could see it accepted spades. The negative spade connector on the new LED bulb fits perfectly into that terminal. The positive spade was too big so I ground it down to fit. I liked that because it removes power from the old unused ballast, and uses a more reliable direct spade connection rather than a tap or splice.
Powered the lights up, and everything worked! There's a little whiny fan noise you can hear with the hood open but it is not detectable in the car. I went for a ride down some dark country roads and the illumination and visibility is markedly improved, and there is a significant difference between low and high beams. I'm satisfied with this product and installation process.