Solid rail but expensive - Kinetic Development Group Modular Receiver Extension, Compatible w/ all 7.62 & 5.56 SCAR Model

This rail offers you a solid option to put a flashlight or dbal on the top front of your rifle without obscuring your vision. However, it does add 1/4 lb up front making the rifle much slower to swing. It is also pretty expensive at about $250-300.