Although it can be fitted on M4/AR-15 (M16A4 / As / Dissipator) platform, the original design of this rail is for SR25/AR-10 platform that uses 7.62x51mm NATO caliber. The SR-25 enhanced match rifle utilizes the newer URX II Picatinny-Weaver rail system, rather than the older Mk 11 free-floating RAS. This rail replicates that same rail system on the SR-25. What this means is that you can turn your M16 rifle with fixed stock to ressemble an SR25 quite quickly by attaching this rail. Of course, the SR25 system uses a larger 7.62 caliber magazine while most AEG M4 / M16 rifles on the market use the smaller standard 5.56 caliber magazine. But hey, you'll have 80% of the look!
Please note that all Madbull / SOCOM GEAR rails require you to retap your AR15 style receiver in order to mount this. You need to get the Madbull Delta Ring Modification Kit (Re-Threading Tool) (either entry level or pro level) to do this. See related products below.