VFC HK417 20 inch Sniper Coversion Kit for VFC/UMAREX HK417 AEG [VFC-VF9-HGD-HK417SR-BK01]

Extended Free Float Rail System with build-in folding front sight.
Extended Outer Barrel (14mm CCW thread).
New type Folding Rear Sight.

http://airsoft.tiger111hk.com/p22505/VFC-HK417-20-inch-Sniper-Coversion-Kit-for-VFC/UMAREX-HK417-AEG/product_info.html