He is also, as always, selling a stock of weapons and armors. As mentioned in the tweet above, he is selling a machine gun, pulse rifle, chest armor and gauntlets.
Armor Version 1 allows you to carry more ammo for Fusion Rifles and Auto Rifles. Version 2 allows you to carry more ammo for Shotguns and Scout Rifles.
Gauntlet Version 1 gives Increased Auto Rifle reload speed and Melee hits replenish Grenade Energy. Version 2 gives Increased Scout Rifle reload speed and Grenade hits restore Melee Energy.