Bests & Worsts Reviews from Amazon

The lamp works well as others noted, but what no one is talking about is the USB power issue. The lamp doesn't come with an adapter, and I see a bunch of people saying it's no big deal because they have spare USB wall adapters (probably from old phones, cameras, etc). I'd bet money every one of those people are under powering the lamp. ALL of these grow lights companies (the flexible neck 20-30W sellers at least) are guilty of what I describe below, and it's quite annoying. The Problem: This lamp is rated for 20W running at 5V DC, meaning that the output current to the lamp is 4 amps (20 W/5V = 4 amps) at the highest lamp setting. I've NEVER seen a typical Belkin, Samsung, Iphone, anything USB charger output 4 amps, they are always <2.1 amps@5V, making their output ~10W (this should be listed on the adapter). So, yes you can use a phone charger, but you'll only be running your 20W lamp at 10W. Also, it's usually not a good idea to run any transformer (that's what the adapter block actually is) at 100% load. Rule of thumb is that you should exceed 80% load for continuous power draw, and powering a lamp for 12 hrs would be continuous use. Think of it this way, when the lamp is at 100% it wants 4 amps of current, but it cannot get it because the adapter cannot provide 4 amps, so it will get the maximum the adapter can supply (~2A), but those adapters are cheap mass produced things. They aren't designed to run at 100% load for weeks and weeks. So you are just asking for issues. What you need and Why you won't find it: What you need is at least a 4A 5V USB adapter, which is NOT easy to find—why do you think one isn’t included? And even the other products that include an adapter are still under powered because they only output 10W, so you cannot win with a USB connection. Why? Because 2.0 USB connections are not approved for >2.4 amps with the exception of USB 3.0 PD (and USB-C which is 30W), which is irrelevant in this discussion. A big reason why is that the wiring used in USB connections are very small (usually AWG 28 or 24), which is too small for 4 amp currents. You’d want about 18 gauge wiring for the currents that this product requires. Ideally, you’d want a power supply capable of 6 amps output at 5V, that would be a 30W adapter. But you'll never find it with a USB 2.0 connection. When I buy these lamps I cut the USB end off and use a screw terminal to power them with this https://www.amazon.com/ALITOVE-Transformer-Adapter-Converter-Charger/dp/B078RZBL8X/ref=sr_1_1_sspa?s=electronics&ie=UTF8&qid=1540163870&sr=1-1-spons&keywords=5v%2B20a%2Bpower%2Bsupply&th=1 Still there is the wiring issue (gauge too small), but I hope this review gets people thinking. Because a lot of people here are plugging this light into old phone chargers, running them at 100% load and leaving them running for hours and hours often while at work. Something to think about.