"THIS IS NOT THE SAME AS THE JG M4 S-SYSTEM RAILS. Originally I though it was so just a heads up. The bottom half of the fore-grip that servers are the battery compartment and the 2 locking screws for it ARE THE ONLY PLASTIC PARTS, the rest is made of metal..the rails mount onto your upper receiver's rail using 3 recoil pins. To install you will have to remove your delta ring and barrel nut and replace it with the barrel nut that came with the rails,your front sight isnt touching the front end of the rail system if any at all so you essentially have a free floating barrel. It comes with a sling attachment point for the rails so you can still use a 2 or 3 point sling. Look up the DBoys M4s System to see how this is SUPPOSE to look like. If you dont have a DBoys then you will have to modify the top rail of your gun OR the S rail's top rail and barrel nut as it is suppose to slide onto the receiver's rails by about 1.5 inches. Alternatively you can choose to not modify the rail but instead move your front sight post up a notch to make room for the "extended rail" .The recoil pins are enough to keep it from moving. Make sure you have a needle nose pliers ready cause the pins are secured with this weird nut. This thing is heavy. If you have a full metal gun with this thing...be ready to carry an 8 lbs gun assuming if you're running optics.
5 stars even with all this trouble cause it does what it was made to do and not what some people wanted it to do and didnt get."