As a travel writer who’s constantly moving through security lines and hotel rooms, I’ve come to learn that the right gear can make a big difference in the overall outcome of a trip. Over the years, I’ve tested some of the most popular travel essentials on the market, but lately it’s Amazon’s clever, under-the-radar travel finds that have become my go-to picks when it comes to traveling smarter. And right now, the online store has released a bevy of products under $40 that are undoubtedly making it on my next trip. These picks are designed to make getting around smoother, way more efficient, and to help frequent fliers avoid travel chaos (think tangled necklaces, dead phone batteries, and neck strains). From compact organizers that keep your checked-luggage in check to multitasking gadgets that save space and sanity, these are the items to add to your shopping cart—prices start at $9.…