Buying guide
Bag dimensions, battery rules and voltage come first. Comfort is the part you decide after those are settled.
Carry-on and personal item limits differ between airlines, and sometimes between aircraft and fare classes on the same airline. A listing that says it meets cabin requirements is a seller's claim, not a guarantee. Check the current dimensions on the site of the airline you fly most, and count wheels and handles, since many bags publish the shell measurement and leave the protruding parts out.
Lithium power banks belong in the cabin. Airlines do not allow them in checked luggage. Capacity is generally governed by a 100 watt-hour threshold, above which you typically need advance approval from the airline, and higher still is not carried at all. Check the watt-hour figure on the listing before buying. A seller who publishes only milliamp-hours has not thought about the rule. Treat your airline's published limits as the authority.
This is the mistake that ruins appliances. An adapter changes the shape of the pins and nothing else. The United States runs at 120 volts while much of Europe and mainland China runs at 220 to 240, and plugging a single-voltage device into the wrong supply destroys it. Phone and laptop chargers are usually marked 100 to 240 volts and travel fine with an adapter alone. Hair dryers, styling irons and small heating appliances are frequently single-voltage, and those are the ones that need a converter, or are better bought at the destination.
What actually makes flights uncomfortable is your head falling forward once you doze off. So the question is whether there is support in front, not how thick it is behind. Traditional U-shaped pillows pack the back of the neck and leave the front open, which does little if your head tends to drop forward. Also think about how it packs. Clipped to the outside of a bag, it takes more room than people expect, and firmer support designs generally do not compress at all.
Cubes and compression bags do not reduce what you are carrying. They tell you where things are so you are not unpacking the whole case to find one shirt. Compression removes the air between garments, which works on bulky jackets and does almost nothing on items that are already dense, and the weight is unchanged either way, so airline weight limits still apply. Choose sizes against the internal dimensions of your case rather than by advertised litres.
For travel inside the United States, prefer a lock security screening can open; anything else you accept the risk of it being cut. Skip power banks that claim far more capacity than comparable products at a noticeably lower price, which is a safety question rather than a bargain. Skip ordering a day or two before departure, where the delivery risk outweighs the product risk. And be careful with listings that sell a dozen sizes and colours under one set of pooled reviews, because the feedback no longer tells you about the item you are buying.
A recommended slot requires a rating above 4.4 and at least 50 reviews together. Below 4.2 goes back to review, below 4.0 we stop recommending. Negative feedback over 8% moves a product off the homepage into observation and over 15% removes it. For batteries and charging products, a safety or counterfeit signal pauses the listing immediately without waiting for a threshold. We do not test products ourselves. We remove the ones with unclear sourcing, unstable feedback, or complaints that cluster around safety.