Augh. I bought this umbrella for it's UV protection, supposed capability in the wind, and because it's compact and pretty. Well, it's compact and pretty and it definitely blocks the sun. Which would be great, if it actually managed to stay open.
When walking my dog in a very light (less than 10 mph) wind, the locking mechanism keep popping open, effectively closing the umbrella. On a 2 mile walk, this happened at least 30 times. I finally gave up and closed it.
It seems like this is one of those umbrellas where you either get a good one, or a crappy one, like I did. It's a gamble-umbrella.

IF you decide to buy one of these, an early warning sign that it's a crappy one is if it's hard to get to stay open. If so, return it immediately. I wish I had.