Not sure how someone could ever give this a bad review, it works great, the charge lasts a LONG time, and it is SUPER easy to program, right from my phone. What more could you want?I purchased this for teaching doctors & nurses in the hospital. Changed the message from welcoming them to the class to whatever subject I was teaching. It was a hit among my students and made my fellow educators envious! Plan on buying more for my staff!have been using it at furconsUpdate 8.21.19...bought 2 blue in tin. (Picture with brightness on 100% then 25%)The first pair was obviously defective due to charging issue alone..However, the second pair wouldn't change brightness either but they held a much longer charge!SO... the latest update to the android app "coolled1248" made 2 HUGE changes..now the brightness slider works!!!!!!!!!!!!!!! I can't stress enough how much this makes the badges last SOOOO much longer and they added a multiple message save library where you store pre typed messages and now just click and new message displayed!!! Instead of having to retype whatever message you wanted to display change...GOOD GOING GUYS AND GALS!!!! (Round of applause)I work for 2 food delivery services and wear 1 name badge to display the company I'm picking up and dropping off for that delivery, and 1 badge on the black tin it came in on my dash board saying "delivery driver returning soon"....The only issue I have left is the deceptive battery estimations. .. very wrong!! Even with the brightness fixed...I use the movie scrolling mode which the manufacturer recomends in their manual, to help save battery and use it at 80% in daylight and 35%ish at night and now lasts almost all day 15 hrs delivering food...turned off in between deliverys...trying their standby or switch on but screen off with the app in between runs to see how that effects the battery longevity.Now I give with NO hesitation 4 stars be honest about batt life and 5 stars it is!!!The brand these seem to be copying and had the verbatim , cut and paste I suspect, description of batt estimations with one HOGE diff the other brand says lasts 5 hours get 2 for all day use 8 hr I assume... tjis is missing from tjis manual... but in defense of this brand it's upload of messages is WAY BETTER AND EASIER than the one I'm talking about...which needs u to hit a button to up load on badge...so better exicution on software side to this brand!!I loved them when I first started using the ,however, when I went to recharge them the recharged in less than 5 min..The slider is set to lowest position 25% light brightness ...even in the dark moving the slider for brightness has no effect nor does setting it at lowest and sending to badge...people LOVE it and it's helping my business and all other app android features work. If it won't hold a charge or change brightness uslessThey said it lasts 10 hours and I believe it would. On full brightness I ran it for a 6 hour event and it was still as bright as when I first turned it on.I bought ten of these for staff in a nightclub so people could pick out a staff member in the dark. We had originally used hang tags with no special attributes, and people had a rough time finding staff members. I adjusted the brightness all the way down because they were so very bright, and they could still be seen across a club that was filled with lasers and strobes and all sorts of other special effects lighting. Out of the ten, I had issues with one, and wrote to VBlab and was promptly given a refund. I was so impressed with that service that I turned around and bought 6 more! I'm still testing them to see how long each one lasts. On our first trial, one petered out at about 3 hours, so I'll be keeping an eye on that one and making sure it is set at a low brightness setting. Most of the others lasted throughout our 5 hour event at fast speed with low brightness. Programming was pretty easy! I downloaded the app, connected it via bluetooth, and updated them easily. I did find that the app instructions were not super thorough, but I figured it out with some trial and error. I wasn't getting fancy, though, just using scrolling text. If you want to use symbols and effects, it looks like there's some trial and error. My largest complaint is that the magnets in the back seem not to be very strong, and we had to use the pin instead. I have some neodymium magnets and may experiment a bit with those. I'll write more when I get my next batch!I love these! I bought all all the colors! I am a Uber Eats driver so I bought these to use for my deliveries and help keep business going. They work very well and are bright! I use some on my windshield to help my customers identify my car as I deliver to truck drivers at truck stops and it helps quite a bit! Can’t see them in the daylight which is bummer but that’s not it’s intended use so I can’t hold hold that against them. I have noticed that they say 30 mins to charge but I have had them charging for hours before getting full charge. One miner thing and that’s in the app. While very easy to use I would like to add or rename the connections of them to something I can remember which one is which. Overall great product! Definitely recommend this!Extremely simple to use. Download the app to your phone (I have an iPhone 8 Plus) and thru bluetooth you update the message just like you would a text basically. Once you press send, it automatically updates! I wear it out to concerts and work functions for fun and always get a great reaction from people as I'm constantly changing what it says.I will list some negatives, but just to note; even with these I still consider it a great purchase considering the price and what it does.-The magnet is pretty weak, if you bump it there is a good chance it falls off.-If you have a real long message, it takes a while to scroll even on the fastest setting so it's better to keep it short and sweet.-Sometimes when you go to update the message and press send, you'll notice it didn't go thru. You just have to reconnect, no biggie but something to keep in mind.Once again, this doesn't detract from the item at all, I would still highly recommend and for the price you can't beat it!