I've had no issues with this. I've had this installed for about a year. About 5000 miles commuting on rough roads and it's held up great, haven't had to tighten or adjust since it was first installed. Mounted to Charge saddle. Vis pro is the best light you can buy for the money also!

Being a shorter rider, I don’t have a lot of room on my seat post for accessories. This seat rail mount fits perfectly between my saddle and seat bag. As of this post, I have ridden nearly 200 miles with no rattling or any issues. It just holds my Vya pro securely and works.

I have this mount. Got it to match the Vya pro light and the design of this is terrible. Because of the ball joints, even with the torque as high as I dare go, light ends up pointed down. There just isn't enough area to get enough friction to keep this pointed oriented rights. I've tried everything including adding friction paste to see if it could get a better hold.

The socket portion also came off the plate that has the two balls attached during installation. Looks like it was superglued. I glued it back and it has not been a problem.

Overall, the design and quality of this product is so bad that it makes me doubt the quality of everything from Light and Motion.

TLDR: don't buy this, it doesn't work and is a total waste of money.

Pretty easy to fit although could do with better instructions. A bit fiddly. Great once it’s on though.