I won a few Jet Wing Duke figures in an eBay lot and I had the perfect idea for them.  I never had the Steel Brigade figure as a kid so I knew I wanted to make my own in Sigma 6 form.

Base Figure: All Jet Wing Duke (Sgt. Steel uses Sea Ops Duke head modified)
Accessories: Jet Wing Duke rifle, belt, knee pads, helmet, pants / 1/6 scale belt and grenades

These were a lot of fun but hard to figure out.  I wanted to pay homage to the original Steel Brigade figure but update it with a Sigma 6 style.  I never liked the tan pants with the green and blue shirt and vest of the original so the Jet Wing Duke pants really fit with my idea for the Brigade uniform.  I kept the blue and green since it's a nice combination and helps set these apart from the normal Sigma 6 uniform.  Sgt. Steel's head got a haircut and that was it for modifications.  I added a custom blue Sigma 6 logo as these guys are a little different from the regular troops.  The rest of the accessories just fell into place and I'm happy with the result, especially the backstory ...

Code Name: Sgt. Steel
Real Name: classified
Steel Brigade Commander

Primary Military Specialty: Infantry
Secondary Military Specialty: Airborne Specialist

Sgt. Steel is the "face" of the Steel Brigade.  He's their commanding officer and the liason between the troops and the rest of the Sigma 6 team.  Steel, like the rest of the Steel Brigade, is never seen without his signature helmet as his identity is classified top secret in order to preserve the integrity of his mission.  What little declassified information is available is this, he was trained alongside the Sigma 6 team and is a specialist in infiltration and urban combat.  Steel is airborne qualified as is the rest of the Steel Brigade.  Though his voice is disguised by his helmet, his personality comes across as very light-hearted and he's not afraid to crack a joke in the middle of combat to break the tension.  But he is also focused on his mission and has yet to fail to complete a task given to him and his team.

Code Name: Steel Brigade
Real Name: various, classified
Sigma 6 First Responders

Primary / Secondary Military Specialty: various

The Steel Brigade is the Sigma 6 equivalent to a special forces unit.  Created by and named for their leader Sgt. Steel, the Steel Brigade are the first to arrive on many missions and do the leg work necessary for the main team  to complete their objective.  From intelligence gathering to frontline combat, the Steel Brigade does it all and all without the accolades given the main team.  In order to do their job effectively the identities of the units members are classified, both to protect them and their mission.  But this doesn't hinder them in any way.  In fact it frees them up to get into places the main team couldn't go near and so they can accomplish things the main team can not.

General Hawk: "The Steel Brigade are the unsung heroes of our team and we couldn't do what we do without their support.  They ask for nothing and give everything.  True heroes all."