I had to buy the wrong item first to become more familiar with how battery heated apparel are sized. Since many are imported, they might be sized smaller for Asians. To say those do not measure up is putting it lightly. For sure, Ororo products are provided in American standard sizing measurements. First I measured my chest which was 2XL, and then measured my stomach which is bigger than my chest, so I ordered the 3XL instead and the vest I received two days later fits me perfectly. I didn't see any apparel sized bigger than 3XL, but with my stocky build, 4XL could even be a consideration if available. Those who stand over 75 inches tall however, are not likely to find an Ororo garment that fits. Not yet anyway. That's too bad because these excellent jackets and vests are made of heavyweight premium materials that provide excellent protection from the cold even without the heating elements energized. Really comfortable when heated.The Ororo batteries are excellent! You can purchase Ororo apparel with or without a battery and charger, but you must use only Ororo products. The batteries are flat and when placed in the provided pocket will not interfere with anything. Much better than the large cubical batteries of some other brands. When positioned in the pocket, the Ororo battery is hardly even noticeable, about the same as carrying a phone. And of course, you can feel the heat when the battery is still supplying power to the heating elements.How long will the batteries supply power?Ororo is on target when stating how long one of their 5200mAh batteries will remain charged. I ordered an extra battery since the highest heat setting will discharge the battery in about three hours. When wearing my Ororo vest however, I discovered that the low setting will keep me adequately warm and comfortable for ten or more hours. Medium setting lasts about six hours. Just look at the button and the bright LED color indicates the heat level it is currently working at. It takes a little over six hours to charge a completely depleted battery.You can be assured that Ororo sells high quality products for the right price. In fact, my first order was the least expensive item, when at the time a full-length jacket was on sale for not much more than the price of my order. Regretfully I had to pass that coat up because I already have several jackets, and a vest provides a little more versatility when worn under one of them. That will also hide the bright LED which may be favorable in certain situations.Ororo is continually improving and adding more efficient products to their excellent product lineup.Ororo products are HOT, and too good to pass up. Winter is just beginning and there will be more chances of cold weather ahead so keeping a charged up heated vest or jacket readily available just may be what gets you thru a freezing cold and dangerous situation. Ororo even packs this vest into its own zipper bag to make it easier to carry in your car. An adapter that fits into a car's lighter socket is also available for when necessary to charge an Ororo battery while on the go.