A USB fan is a small and portable device that's handy for personal, close-proximity cooling. As the name suggests, it's powered through a USB connection, such as the one in your computer, a power adapter that you plug into a wall outlet or a portable battery. Some can be self-powered using an internal battery that you recharge — over USB, of course — and, in turn, some of these models can even be used as a portable battery to add some charge to a phone. Despite their size, USB portable mini fans can be powerful, and most offer different speed settings. They won't cool down an entire room, but they can keep you comfortable when used at a close distance, such as an office desk or bedside table. Best of all, they are inexpensive. This small desk fan has three-speed settings — soft, natural wind, and strong wind — to keep you cool. Depending on the speed setting, the 2,200mAh battery provides between three and nine hours on one charge. There's blue backlighting you can use at night and emergency light for when you're in a critical situation. Some people experience respiratory symptoms in the summer months, when the weather is hot, and the air contains more allergens. Air conditioners and fans can circulate dry air through the room, and air conditioners remove any moisture from the air. A humidifier may be beneficial during this season. However, people are more likely to benefit from a humidifier in the cold months, when cold air dries out the lungs, nose, and lips. Also, some types of central heating can dry out the air indoors. Insect repellent maintenance cost is low, and it is easy to use mosquito killer products. All you have to do is plug the mosquito trap into the USB and observe all the annoying and annoying mosquitoes in your area. The mosquito killer has a series of photocatalyst lamps, and the mosquitoes cannot resist and are attracted by the trap. The fan then sucks the mosquitoes inside and prevents them from escaping. The countertop blender has a pitcher with spinning blades in the bottom that mounts onto a motorized base. More powerful and with more settings than immersion blenders, they can blend, mix, puree, grind, chop and even crush ice. If you cook often with vegetable purees or you love frozen drinks and smoothies, you will definitely want a countertop blender. Their reputation of being difficult to clean is a myth. Which blender you choose depends on your kitchen series needs. If you find that you do not work with frozen or hard ingredients often, the immersion blender is a space-saving gadget that can work in ways a countertop blender can not. Likewise, if you would rather have a larger appliance that can do more, you might prefer to get just a countertop blender. If you have to sleep with a night light lamp on you might think that blue and white lights might create a calming sensation and help you sleep best. However, a new study involving hamsters suggests that blue light had the worst effects on mood, followed closely by white light. For years, consumer electronics companies have competed primarily through technology, by cramming ever more features into products in a race to offer consumers the latest and greatest. But this approach can be fruitless. Even in the best of times, many manufacturers struggle to make money: despite falling component costs, intense competition can restrain price increases, and rapid obsolescence often makes it necessary to discount all but the very newest products. 内容：