Or get some 550 para cord, and use that mil-green tape for a real SF look, at a cheap price.
If your asking how well they preform, I personally use magpuls for all of my rifle mags, Minus the 249 box......
They help keep the mags easy to reach, they look great, and I find they prevent metal airsoft mags from rubbing excessively in pouches, causing less noise, and preserving the mag paint, if thats something that you care about, some do, others like the "used" look on there mags.