I have never written a review, I felt this product was worth a share. Background ; I work in a technical capacity , Electrical & Mechanical and had low expectations for this product. The Problem with many portable home AC units: The HOT air exhaust is just below the COLD air intake, the exhaust hose on my unit becomes almost too hot to the touch during operation, so the cold air intake is drawing heated air in that it must then cool to make you comfy. Additionally the HOT air exhaust duct going to your window or wall is radiating heat BACK into the room as well just like a heater. AC or Heater, which one is it? Is this good for your portable AC room cooling Efficiency: NO, it increases cost and impacts the ability of the unit to do it's desired function, COOL Your Room with a typical hose found on most. Results, two areas of interest: NOISE: I immediately noticed a reduction in the horrible noise and oscillation from my AC unit , I could not hold a Zoom call in my office it was so distracting with R2D2 ( my ac unit nick name) placed 10 Feet away. After the Sock install I was able to hold a Zoom call with no issues. I did not expect this at all. Noise down at least 30 percent on my unit I would ball park guess. Now that I think about it, all of the vibration / sound was being transmitted through the exhaust duct, and the ribs were vibrating acting like amplifiers also sending noise back into the room along with HEAT. It makes sense in reflection. COOLING: The unit cooled my room but not aggressively without the sock the previous summer, after the sock install the exhaust hose was only slightly warm to the touch, previously almost too hot to hang on too! I live in Desert with 120 deg heat in summer peak, All that heat was being transferred back into the room, like a dog chasing their tail. Wow, I don't know what they are using for insulation? It's thin but VERY effective on my unit. Now the room QUICKLY gets cold, the unit cycles on and off frequently, previously it just ran wide open and almost never cycled. What a difference. Definitely Noticeable and using less energy obviously as well. DOWN SIDE: If you could call it that, The Sock is not easy to install, it may take two people, It certainly did in my case. But this is why it was effective for noise in the end as it grips the hose reducing vibration and heat transmission. My install Approach: ( yours may vary) Remove hose end couplers , collapse hose fully and push the collapsed hose carefully to the center of the sock one person holding the sock one person pushing. Then gently expand one end of the collapsed hose a bit at a time inside the sock, then the other side until the hose is completely expanded, push the sock excess back over the hose to install the couplers (hose ends) or fold over as in my case. Install hose and fold back any excess to cover anything you can with the excess if available. There is no Give to the sock, so patience is key. On that note, the maximum bend radius will be slightly reduced due to the new cover, so if you are using very tight bends beware, 35 deg bend was possible for my install only, rough estimate. Certainly nothing beyond 45 deg seems possible in quick tests I performed. Overall: Astonished with my NEW ac unit, I am now wondering why these are not included on these types of AC from the manufacturer, I am very happy with my decision to take a chance. My experience: Quieter, Cooler, Less energy usage.