I originally bought some CFL style UV Black Lights (3 of them) to go into a 2 car garage for a glow party we were doing for my daughter's birthday. 2 of those lights were in the center of the room and 1 more was on the wall. Those lights were just not strong enough for a 2 car garage (maybe if i had 8 of them they would have been enough). So I started checking around and found these. I mounted them on the walls, opposite each other, and they were just about perfect for a 2 car garage. My only (minor) complaint with them is that there is no on/off switch for them. When you plug them in, they are on. When you unplug them, they are off. However, I knew this before I purchased them (From another reviewer, I think) and I was okay with that. That aside though, these really were a major reason why my daughters glow party was so, so, so successful with the kids and adults, too. I reviewed some UV tape, UV balloons and UV paint that we also used, that I would recommend to go with these lights for a glow party. Glow Hard or Glow Home!

P.S. please keep in mind that my garage walls and ceiling are all painted black. Only the floor is not black, it's just cement color.

UPDATE 7/21/2018

I'm adding some pictures that I took with the camera on my phone (SAMSUNG Galaxy S8+, no flash). Pictures are of UV reactive tape and UV reactive balloons that I reviewed elsewhere. This will show what the tape and balloons look like with these lights shining on them. Pictures are labeled to show distance from the lights, too, for your reference.

Small, but bright. You need a bunch to get a lot going on but it's cool to point at things. Don't look into it though

This really made the black light paint in my Halloween scene pop. I only gave it 4 stars because even though it made the scene really come to life by illuminating all of the paint it didn't do much as far as lighting up the scene itself (which I thought it would do) Once I added a green flood light to my witch shack, it really brought everything together. If you are looking to add light to a scene, this alone won't work, but it does a great job of reflecting any blacklight or glow in the dark paint. A must have for your Halloween scene.

I used to use the incandescent blacklight bulbs but recently switched to those LED blacklights. I mostly use them for small to medium rooms, typically a size of a two car garage (smaller than 200 square feet). Here is a list of blacklights which I bought from Amazon.
1. The incandescent backlight bulb which is 70W, I used one bulb to light up a room, not efficient light and it looked weak, the wattage rating was honest but it became scorching hot after minutes of use and I stopped using it.
2. The 18W UV blacklight bar was bought on Amazon from another seller, worked well but it had dishonest wattage rating (20% lower than advertised).
3. HouLight 10W LED UV blacklight was highly efficient and works to my satisfaction and two would cover the area pretty well (maybe even one light would do). Good quality and measured wattage matched with advertisement. Not much heat during the use. Highly recommended.
4. A very similar looking 10W LED blacklight I bought from a different brand. At first I thought it looked almost identical to my HouLight but after a very close look I realized the LED chips are smaller and the cable was much thinner, also the wattage rating was dishonest (10% lower). Overall a less quality light and not recommended.
In summary I found it wildly common that LED lights on Amazon have dishonest wattage ratings, as layman usually don't have the tools to discredit what was advertised, it is still rampant on Amazon and even more so with the high wattage LED lights. That's why I bought the wattage meter to measure all of my LED lights in my house. By all means wattage isn't the only virtue but roughly represents the output light for most common LEDs. Rule of thumb is that a 50W LED (blacklight or not) light is close to the size of a shoe box due to heat requirements and so on -- you get the idea. So I would not trust a cheap and small "high wattage" LED light (blacklight or not) as they cannot defy physics, I also will never buy from the same seller again if their LED lights have false ratings. Again for small to medium size rooms there is no need to go with big wattages anyways, as 10W-20W LEDs are typically adequate. With blacklights it's kinda tricky since there isn't much visual light (well, it's UV). You would use them in the dark with fluorescent tapes and neon paint or similar things to decorate the space, the power of the light will then be revealed and the decorations will glow wildly even from a big distance away.

I used this inside a small gym/ indoor basketball court. Sorry I cant give a better size reference. If you know a church basketball court... that size. I used TWO of these "flood lights" and one bar light and it worked so they could play glow in the dark volleyball. (One would not have been sufficient). So depending on the area you are trying to illuminate... but the light is bright and makes the right colors really pop. I had a bar black light 10-ish years ago and it did not illuminate much. These are much better!