K&F products are all good quality and this magic arm/clamp is no exception. Made entirely of sturdy metal both the arm and clamp are very solid when locked. When unlocked the arm bends easily in the middle and the ball-heads at either end can swivel at will. They also include a female-to-female 1/4-20 adapter and a cold shoe mount. This can be useful for mounting accessories like flashes, lights, monitors, microphones and so on to a camera or to a tripod or light stand. The clamp lets you clamp to a pole or tripod leg when a 1/4-20 mounting hole isn't available which can be good for mounting action cameras or lights to things like bikes, roll cages...etc. Once you tighten this securely it's going to stay put and not come loose. The only exception to this is the 1/4-20 threaded items, these don't have any locking or anti-rotation devices on them. Even if you tighten them really well, under-stress or vibration they can start to loosen, allowing whatever is mounted on them to turn. This is an issue with most magic arms. If you have problems with this, the best solution is to apply a SMALL amount of non-permanent thread locking compound to the threads.

Both the clamp and the arm are pretty solid and should be able to carry quite a bit of weight. However if you are mounting this to the hot shoe of your camera, be sure the hot shoe of the camera is sturdy enough to handle the weight.