Read the review on Amazon"In 15 minutes, I was able to cool the unit from a reading of 87°f to 36°f using the supplied cable and charger, in a room that was 74°f. I see a lot of complaints that are related to improper use. If you are having problems, read and understand this whole review. This unit does work, and it's limitations are in the instructions, but it may take an engineer to understand the limitations and explain them properly.I am an electrical engineer. And I happen to have very specific knowledge about how this unit operates, and why some people have issues with it. This is a 10 watt rated peltier junction refrigeration device. As long as the fan works, this unit will be functional as the solid state nature of the cooling device should have it last a lifetime. But for it to work for you, you will need to understand how to power this unit. This unit has a short USB C cable, and requires a power supply that can handle 5v at 2 amps to supply the rated power of 10 watts. If you don't use the power supply that came with it, you may have trouble finding USB ports that put out enough power. The standard USB2 port can only put out 1/4th the power this unit is rated to use. If you plug it into a standard USB port, the unit may only provide a tiny amount of cooling, and it may not be enough if it is in a warm location.This unit draws 1.5A of power when it is cooling, and if your power supply can't put that much power out, the cooler may not have enough power to do the job.This is important to understand... This unit can provide a maximum of 50° of cooling. That means if you want it to never get above 47° it must never be stored above 97° with insulin inside... If you put it in the trunk of the car on a 110° day in the Texas sun, the inside of the trunk may get as hot as 150°. at that temperature the coolest your medicine will be is 100°. On a hot dashboard where I have measured temperatures of 170°, you can expect internal temperatures no cooler than 120°. The 50° cooling this unit provides is a real limit, so plan accordingly.This is a reliable device, but power cords are frequently mistreated, so buy extras, and don't buy the cheapest cord you can get. To provide the 2 amps of power, you need a proper thick usb A to C cable that is capable of carrying power, so look for cables labeled "quick charging" to insure they are designed to carry the rated power. If you want a long cable, it must be thicker, so get one rated for 100 watts or more (for best results). The longer the cable, the less cooling you will get, so even though this is a 10 watt device, the reduced voltage drop from a 100 watt cable will provide help you get the maximum cooling.And if you use a power bank, be aware you will be drawing 8 watts when it is cooling, and in a warm location that drain will be continuous. Most power banks are rated at a higher wattage than they actually support, so it is best to assume the power bank will only put out 25% of the claimed power, but it could be as much as 75% from a high quality brand, but most you see on amazon are going to be closer to the 25% range. This unit draws 1.5Amps, that is 1500 miliamps. So to run this unit for 24 hours in a warm location, it wants 1500 miliamp hours of power per hour, so 36,000 mah per day. a 30,000 mah power bank *should* run this for exactly 20 hours, but in my experience you can expect 5 hours from cheap power banks, and perhaps 15 hours for a good power bank rated 30,000mah. The reasons the ratings don't provide real-world results is the batteries are 3.7v rather than 5v, so power is reduced by stepping the voltage up to 5v, and it is further reduced because 95% of the batteries from china do not actually hold the amount of power they claim, so the rating of the power bank will be off by however big the lie was when they sourced their batteries.And finally, this unit turns off cooling at 36° and turns it back on at 46°, so the temperature will cycle across that range. I use two insulin and one liraglutide products. The strorage instructions are long term storage in the 34-45°f range, and storage BELOW 80°f for up to 30 days after first use. I have changed brands several times, these temperature ranges are common to all of the insulin/diabetes injectables I have used. so if you are carrying a 2 week supply, for 2 weeks, then 79°f is a target temperture to stay under (you guys that think you must have insulin be refrigerated all the times are either wrong, or you are using a cheap and unstable form of insulin. The point is I read a lot of reviews of people that claim cooling requirements that may not be actually true. Read the whole label on your injectables, not just the part that says keep refrigerated. Mine say below 80 for up to a month. Most of yours will too. The important thing here is this means that the maximum powered storage temperture for a 2 week supply is 79°f, which with the 50°f cooling capacity means your medications can be kept safe up to around 120°f if fully powered and out of direct sunlight. Direct sunlight will add heat.The biogel will work at higher temperatures, but the hotter the shorter it lasts. If you are packing without power, I would generally trust the ratings of the biogel, as that is a reliable source of cooling. If you travel by plane, be aware that the biogel must be frozen to get past security. If it is melted, you will not be allowed to have it in carry on luggage, and they will make you throw it away. So using the biogel for air travel requires you to have it fully frozen in security, or you will need to pack it in checked luggage. But if your luggage is lost, all bets are off as to the condition of your medications, as they might spend a week in a metal box in the sun at an airport, so a reason TO and a reason NOT TO store in checked luggage. Decisions decisions. Buy two coolers and store half of your supply in checked luggage and half in carry on.So to recap:- provide power from a "fast charge" capable power supply- Provide at least 10 watts of power on a good cable- Do not store it at temperatures exceeding 50°f of the desired medicine temperature when powered- Cools quickly when empty, probably needs an hour or so if full (unless you prechill as recommended)- If you are having problems call the number on the door hanger- The warmer it is, the longer this will take to cool down (reality is harsh)- Test your power supply and know your limits- Cars can get really hot, 75°f higher than the temperature outside is easily possible, so this cooler can't do it's job in a hot car for long- The temperature of the display is that of the cooling device, you will see it cycle up and down from 36° to 46°, but the ACTUAL temperature of your meds will be the higher of the temperatures you see it cycling between.I did several tests using the provided charger, and the unit works GREAT. It performs up to the claimed capabilities. It cannot do the impossible... nothing can. I paid $200 for this, I think the value justifies the price. There are plenty of biogel based coolers for 1/8th the price, I still think the value justifies the cost of this unit. I'm an engineer, I could make one of these for under $50, with about $1000 worth of labor. Buying one already made is a good value."