they do the job there supposed to

The sun glasses are big and sturdy and easy to flip. The frame and flipping mechanism seem relatively robust and are unlikely to break under normal use. the lenses themselves are a bit more flimsy, but should be ok without too much abuse. The flipping motion is relatively smooth and easy to do while wearing or holding the glasses in your hand.

However, I just can't stand the color -- it's...TOO dark.
Every time I wear these sun glasses I can only stand looking through them for 10 or so minutes until I just get really annoyed. They almost cast a grey fogginess over your vision (vs. normal sun glasses that simply dim the brightness of incoming light). I gave these to my girlfriend and she agrees about the color, but she enjoys the strong, large, wide, flippable characteristics enough that she continues to use them.
Warning, though: you will NOT look cool wearing these flip sun glasses haha.

Update: These have survived car use for numerous months now -- no issues! I still can;t stand the color, but my GF still likes them!

I have used clip-on sun gasses episodically for years in situations where I will be going back and forth between indoor and outdoor lighting--far easier to take the clip-ons on and off then having to carry both regular prescription glasses and prescription sun glasses and switching those back and forth. At the same time I have always worried about scratching the lens on my glasses and taking clip-ons on and off remains a pain, so I have frequently quit using them and simply suffer in one lighting situation or the other. I have also tried flip ups thinking they would be the perfect solution but the hinges never stood up to use and I still worried about scratching my lenses. Tried these and find them to be the perfect solution. The rubber on the attachment point protects my glasses and the lens of the flip-ups are slightly separated from my glasses so they don't scratch. Some have complained that the latter allows sunlight in under certain conditions but I have not found that to be a problem. As for the reliability of the hinges, I recently completed a 1,800 mile bike tour and wore these every day, frequently flipping them up or down depending on conditions. No problems at all and they even stayed in a horizontal position when going downhill at speeds over 20 miles an hour. I must like them as I now own three of them stashed in different places.

These really do work. I wear glasses and I'm able to put them over my glasses. However, if your glasses are thick, it could be challenging. But they really do work. Nighttime driving is no longer stressful.

I like them for driving, makes colors sharper, flip up to read dash information.