When initially researching these housings, I was not able to completely understand the various comments people were posting on the tabs. I did see that people were successful in figuring it out, so I bought the housings and I did figure it out.
These are 6 inch aluminum body remodel housings, the air-tite version and approved for IC. As others have commented, the aluminum is light weight and can be bent. They come six to a box in the store and the tabs are likely to catch on the housing next to them and your odds of picking a random housing with one of the four tabs missing appears to be greater than 50%. Check your housings as you pull them out of the box and make sure you have all four tabs. They are easy to pop back in if they have been pulled free from the housing. Also, check for bent housings...best to start with straight ones and try to keep them that way, although you can bend them back to shape.
Installing the housings...caution, be sure you know what is above the ceiling if you are cutting a hole into the ceiling above you. I had to work around an AC duct, water pipes (one of which took a 90 degree turn in the middle of the room and cut through the joist bay), and other electrical runs. I used a Milwaukee adjustable hole cutter with the drywall dust catch plastic pan on the bottom...worked well. I set the hole diameter for 6 1/4 inches. The resulting hole is tight, but the housing will go through with a wrap from the palm of the hand. I would not go up to 6 1/2 inches. The template that comes with the housing is also 6 1/4 inches in diameter. Before placing the housing into the ceiling, determine if your downlight requires the housing to be adjusted to the full depth. I used a Cree TW Series downlight, 85 watt equivalent (great light with 1100 lumens, CRI of 90+, and dimmable). This downlight would not fit into the housing at the factory depth setting. There is a wingnut inside the housing: loosen it, slide the internal housing piece back to increase the depth capability for the downlight, then tighten the wingnut. See my attached photos. Your downlight may not require this adjustment.
You must connect your wiring before placing the housing up into the ceiling. Using the quick connectors is easy, just strip 1/2" of insulation from the wires and firmly push them into the connectors. Visually inspect through the clear plastic that you seated the wires fully: you do not want to have a light not come on and have to pull the light and housing down out of the ceiling later on.
Once the housing is up into the ceiling, you must lock the four tabs in place. If you have been reading the other reviews, this is the biggest issue with this housing. Several people reported success with bending the tabs...I found you don't need to bend them at all. If your ceiling drywall is 5/8" thick, you are going to need to use a large screwdriver to put the necessary force on these tabs to get them to lock into place. If your ceiling is 1/2" drywall, you may be successful with just using your fingers. There is some gray insulation material on each of the four spring tabs...this spongy gray insulation hides a small sub-tab piece of metal that juts out from the tab which is where you will want to place the blade of a large, standard screwdriver. You can feel this subtab with your fingers. You can pull the spongy material off one if you want to visually see it. With the housing up in the ceiling, I pushed the spring tab up against the side of the house, then placed my standard screwdriver blade tip against the subtab. While keeping pressure against this subtab, I then used the palm of my hand to rap the end of the screwdriver, driving the spring tab upward and back against the housing. Don't rap the screwdriver too hard, you might push the tab all the way through the side of the housing. Once you figure out how much force is needed, the spring tab will lock into place and you will quickly understand that locking the tabs in place is very easy. You will quickly move through the other tabs after this. See the attached photos.
At this point, remove the plastic socket protector tab, if it is still in place. Screw in your downlight connector, then pop your downlight up into the housing. There are several different mechanisms to get the downlights into the housing...consult the instructions that came with our downlight. I tapped/twisted my downlights as needed to get them to remain flush with the ceiling.
Pros: Easy to Assemble, Fast / Speed, Functional
Cons: Difficult to Assemble