I have something similar (not those exact units) on my Fizzer 400.
The size of the fins on the back probably means you will not be able to use the dust cap on the back of your headlights. This shouldn't normally be a big problem.
Brightness good. Beam pattern ... meh. The problem is that a filament emits light more or less uniformly all the way around but a LED element only emits it on one side of whatever surface it is mounted on and not evenly. So, the light ends up being more concentrated in one area, with less outside of that, when it strikes the reflector. The practical result in my case was that the light pattern on low beam has a "hot spot" in the center but less towards the sides. High beam pattern is very uneven, to the extent that it's better to just leave it on low beam. Having said that ... even with the stock bulbs, these headlights do not have a good beam pattern. They spill too much light out the sides, in close to the bike. That has actually mostly been solved with these ...
In my particular case ... my bike has two headlights with independent aim adjustments ... so I used the separate left and right horizontal adjusters to aim each housing outward a little, and the result (with having two headlights on together but aimed outward a little so that the two "hot spots" are sorta next to each other instead of completely overlapping) is pretty decent. If your bike has a single bulb on, you won't be able to do this.
The Fizzer 400 has a particular problem in its original form, in that it uses two dim 35-watt bulbs that are physically the same shape as H4 (High and low beam) but are about as effective as holding a candle in front of the bike, and the charging system isn't robust enough to support using two standard 55-watt H4 bulbs in place of the 35-watt bulbs. The two LED H4 replacements (which pull 20 watts each) aimed splayed outward a bit to cover up the beam pattern issue, collectively work much better and the bike is actually enjoyable to ride at night instead of being scary.
Bottom line ... If your stock headlights completely suck and are weak with a mediocre beam pattern (like mine were) then you have a good shot at these being better, although likely still with a sub-optimal beam pattern. (can't make silk out of a sow's ear) If your bike has decent headlights with good light distribution in stock form, it is very unlikely that LED replacements for the stock halogen bulbs will work as well.
