Since my crank has no mounting holes, I was struggling to find a chain guard that would work on my giant talon. Stumbled across this and I'm glad I did. My chain would fall off at least twice every time I hit the trails. With this on it stays in place. It does require a bit of fiddling to get it lined up right but once you do everything stays locked in.

It's a little ugly, but it works perfectly. I've got a Schwinn Axum and the stock drivetrain doesn't have a clutch, which means it was constantly dropping chains. It got so bad that I wrecked a cassette, and eventually I even snapped a chain and tweaked my derailleur. The bottom bracket on my bike doesn't have mounting available for a regular chain guide or bash guard, so I had to go with one like this that can be mounted directly to the lower seat tube. I installed it a couple of months ago, and haven't had one drop since.

En un inicio tuve preblemas con este pero era solo falta de alinearlo bien, si queda bien alineado va a cumplir au trabajo al 100%

Helps keep your chain on the sprocket would recommend to anyone switching from a 3 speed to a single

After one too many times of one or both of the following it was time for a solution:
1. Chain pops off to the inside while in the lowest gear
2. Pant leg caught in chain
This chain guide looked to be the absolute PERFECT solution so I decided to give it a shot.
Upon opening the box and checking the guide out it looked to be of high quality and VERY well made
Unfortunately when I tried to install it where it was designed to be, I was unable as it would contact the shock.
Hmmm... I was just about to return it when I thought, "As much as I hate returning items, there must be some way I can make this work"
I tried simply flipping it over so the mount was BEHIND the seat-post and adjust it as close as I could to make it work. However, with the actual guide so far 'behind' where it should be, the chain would contact the guide in both the lowest two and highest two gears.
Ok, that won't work so let's give it one last shot before returning it.
I had a 3/16" thick pice of super hard plastic laying around (can't remember what is was from... something I used on my modified Samurai 4x4?) and it already had two holes the same diameter as the original guide screws and 1-1/2" apart, which appeared to be the distance I needed to move the guide forward.
And whada'ya know, it worked PERFECTLY!
To be sure I took the bike out for a 16-mile ride over rough terrain (more off-trail than on) while using all 12 speeds (bike is a 1 x 12) and had no problem with either issue #1 or #2.

So... with just a little bit of ingenuity and some 'scrap' material I made the guide the perfect solution.
As high a quality as this guide is, IF it was more adjustable so it could be flipped over and still work I would give it a 5++ if not higher.
But as it stands, I can only give it a 4.