Usually I like to wait a bit and try whatever product I buy before writing a review. And I can say with CONFIDENCE this is a great purchase. The velcro hasn't come loose. Buttons seem sturdy. It's comfortable and is concealed well if you have a normal fitting or "baggy" T-Shirt. And holds a 8oz Flask well.
If you have a 6oz or smaller flask, try to get a riser so you don't have to dig into the holster itself. Other then that retention is great, you forget it's there unless the flask is cold or you're sitting down in a weird position. Easy to one hand and grab my flask even with a coat on.
10/10, would drink again. Makes me feel like the King of the Rave.