Yankee Hill Machine 7.28" SLR Smooth Midlength Rail System
SLR (Slim, Light, Railed) series.
The SLR addressed the top two requests of customers: to have a thinner lighter handguard and one that would accept most aftermarket piston systems. Both are features of the SLR rail systems.
The new profile of the SLR allows for most piston systems to be used while maintaining a top rail that co-witnesses with the upper receiver.