They promise to drastically reduce the current draw while giving a brighter light than the old fashioned filament style bulbs. With resistors built in, there's no need to add a load to work with the existing flasher.
Installation is easy, just remove the tail light lens and replace the old bulbs with the new LEDs. They look clear, but actually give a red light when powered.
The new LEDs are on the left and the old bulbs still on the right. I can't say that the LEDs are that much brighter in the daylight, but they are certainly no worse.
The proof is in the testing and early results are good. The first thing I notice is that when flashing there is no fluctuation in the voltmeter reading, where there was a very clear "tic" up and down on the needle before.
A quick drive on my favorite test route with the headlights ablaze got the cooling pump and fans running. The voltmeter was showing a constant 12.5 volts, and it held steady at that level when the turn signal and brakes were applied, so I'm going to declare success.
The next step will be to swap out the old sealed beam headlights for LED replacements to get a brighter light out front. At around $260 each ($520 a pair) though, that will have to wait a while.