The Geissele Super Duty is an AR-15 platform rifle sold by Geissele Automatics, based on the URG-I configuration of the M4A1 in use by US special forces units. The original URG-I carbines were only ever used with original M4A1 uppers, which are black, and FDE rails, so Geissele markets their rifles with black receivers and FDE rails as "URG-I clones" and every other configuration under the Super Duty name.
The URG-I's replacement of the M4/M4A1 Block II has led to it being colloquially referred to as "M4A1 Block III", but URG-I rifles are NOT an officially adopted configuration by U.S. SOCOM, and thus cannot really be referred to as any actual variant of the M4A1 (hence the Super Duty being it's own page, and not a subsection under the M16).
It is also sold by Geissele as just an upper, to be mounted on any AR-15 lower.
All are just the upper, in 10.5" URG-I configuration, mounted on a BCM lower, suppressed and used with Trijicon MRO red dot sights on Geissele super precision mounts, a Streamlight Protac weaponlights, Magpul PMAGs, MS3 strap slings, Insight AN/PEQ-15, and Rugged Micro 30 7.62 suppressors.
