These were made specifically for Sterling Arms International as a lightweight, match option for the AR10/102 platform.
SPECIFICATIONS
Calibre: .243 WIN 
Length: 19
Weight: Light Profile 2.2 lbs
1/10 4R twist
416R (rifle grade stainless steel)
Muzzle threads are 5/8-24
Uses standard .750 gas block
Double stress relieved during manufacturing
Utilizes a standard DPMS pattern barrel extension
Hand lapped and honed for match performance.