Quality of materials, used in airsoft replicas, is not the best. Materials are cheap; springs are very soft, for instance. Especially magazine release springs will cave in under little pressure, which means that your precious gaming time will be used to hunt down magazine for your GBB, which went AWOL.
Magazines are quite costly. In addition, it is bad form to litter the playground, even with expensive magazines...
I've seen many improvised solutions, including duct tape around the base of the magazine (leaves sticky residue, looks unappealing), taking out magazine before holstering (defeats the purpose of the side arm) and improvised solutions, made out of bicycle tube. I used this solution for quite some time and it is very efficient, but looks very cheap.
Magguard is basically a hi-tech version o the aforementioned bicycle tube type solution, which has one very annoying feature: it becomes brittle over time and snaps. No such worries with MagGuard, though- it is made out of elastic material and Velcro, which means that it will last a very long time, providing you take bit of care.
Video guide courtesy of MagGuard. Installation guide is also written on the package:
To install MagGuard to your automatic pistol, turn your gun upside down. With the mag removed, slide the MagGuard over the handle of your pistol. Make sure the seam is facing the trigger. That's it, you are ready to to insert the mag and connect the straps. Now you can be assured that your mag will stay in place whether in your holster or in your hand. MagGuard "always on duty..."
Everything written there, stands. MagGuard does not interfere with magazine change and it is low profile enough it doesn't interfere with holstering and unholstering the weapon. Its design also facilitate magazine change.
You simply need to snap open the Velcro, change the magazine and snap the both halves of the Velcro back together. This is one time purchase- MagGuard can be used on most replicas, including HiCapa and Desert Eagle. In other words- MagGuard fits replicas with thicker grips (or magazine bumpers at the end) just fine.
In conclusion- it is straightforward, simple, effective. Go treat yourself with one.