Beepswrote a review of G-Form Pro-X Elbow Pads on August 7, 2018
Familiarity: I've put it through the wringer
Great cost to value. They fit great, they fit in a cargo pocket really well (if you're doing mellow climbs in warm weather, on the way to terrain you'll need them for), and they protect well for scrapes and minor bumps. These aren't going to do a ton to protect your elbows from huge collisions, but for the size and comfort, 5-stars all the way.
Size is a weird thing. I wear L to XL t-shirts, and have fairly muscular arms, and I wear a large in these pads. They're pretty snug, but that's probably what you're going for.