Been using this for dark early swims in ocean. So far it has worked as claimed. No leaks. Bright enough to be seen by other swimmers.Glad I was able to get this at a decent price. Since it's fall in the northern hemisphere, my daylight hours are getting shorter. In order to stay safe during evening runs, I flipped the battery to change it from a steady light to a flashing light. It's bright and keeps me from getting run over while out on my runs. I wouldn't hesitate to by it again.We live on 20 acres and the dogs love to run around and explore. Unfortunately with the sun setting earlier in the day during the winter, they are often out at dark. This light clips on to his collar and is very secure. Every time I go to let them out I just have to give it a twist and it starts flashing. I can easily see them up to a 500 feet away even through the trees.Im confident that our neightbors wont have issue seeing them while driving and they wont be mistaken for any coyotes :)The lights are fine. I gave 4 stars because one shipped with the lens too tight so the batteries were dead on arrival. It’s a problem with the shipping/handling, not with the product itself.Works well for lighting up the corners of my carport at night when I need. Their customer service was wonderful in resolving an issue I had.I keep this one and a yellow one on my endurance bag for the long hauls through the night. Strong, study and they can’t turn themselves off. The batteries have lasted me about 4-5 years totally worth the money.I use these for swimming at night in the ocean.It is more fun and festive to use several.And to last minute share - so buy several!Anxious night swimmers when everybody has one or 2 of these.I am an avid runner and my runs take place at 4:30am. No matter what the season, it is pitch black. For my safety as well as a courtesy to drivers, I wear two of these lights. These lights are extremely bright! It's like my body is surrounded by a halo. They are easy to use and will last for a long time. If you need to change the battery (that hasn't happened yet of course), it's super simple. If you run or walk in the dark, you MUST get them!Bought this light for night swimming. It clips easily to a costume and is bright enough to make me visible to others from the beach. Will probably order more.