I haven't experienced any extreme temps yet, but I can tell a difference in the garage. Easy to install, but for a door like mine, you have to do some cutting to get behind the braces, but still, did the entire door in 3 hours. I would have given it a 5 star, but for Styrofoam with a plastic covering on one side, I think it's over priced. But if it doe the trick it will be OK.

Gave 5 stars cos I'm sure it's good but found out that since the two boxes of insulation will add 30 lbs to my door, I'll need to change out my tension spring. Decided to return it, but UPS and FedEx would have cost $210 due to the size of the boxes!!!! So it's sitting in my garage taking up space. Be aware that you won't be returning it cos you're responsible for shipping costs.

I only bought 1 kit, planning on the next kit soon. my wife didnt want to sacrifice our windows so I had to figure out a way to cut them out so I can eventually put something like plexiglass over the openings for an air cushion. I had foam cutting blades already on hand and they work great in a jigsaw btw. now I just need my second kit for a 2 car garage and to finish off the windows. the reason I gave it 4 stars and not 5 is that once cut the vinyl facing is quite brittle, if you look at my pictures I re-inforced my door with strut and self tapped the strut pieces on so I had to sneak past them and even on the full pieces I snapped them a bit. didnt break the vinyl coating though but on the 1 inch sides I accidentally did, this was probably my fault and NOT a product defect. also note that my aluminum garage door already had existing 1/2" vinyl faced insulation so this is adding 1 1/4" to that so it was really tight, in my case I had a lot of measuring to do, if you dont have windows or existing insulation than go for it for sure! only time will tell energy savings once I pad the windows and finish the bottom half of my door. even so running a space heater in the dead of Wisconsin winter I'm at about 68 degrees and that's with my exhaust running on low.

update: 1-27-2019

I finished with the second kit today, I still need to order and affix solar paneling over my 8 windows so right now not a huge difference in temperature, it is about -18F in N. Wisconsin right now though and with 1 electric heater going my garage is at 60 degrees with my exhaust system on low.

Very pleased. It was not enough for 2 car garage... might need a pair

Good at keeping heat out of the garage and easy to install, did not come with glue though.