[1] The M400 is an air-cooled, direct impingement gas-operated, magazine-fed carbine that is based on the earlier AR-15 rifle.

[2] Depending on the variant, it can be chambered for 5.56×45mm NATO or .300 AAC Blackout cartridges, and may have a fixed or telescoping stock.

[3] The SIGM400 is a semi-automatic firearm in either rifle as the SIGM400 Classic, SRP, Tread, Elite, Predator or pistol as the Elite PSB, intended for law enforcement, military and civilian markets.

It fires from a closed bolt and uses a direct impingement gas system.

[3] The .300 AAC Blackout model is tailored specifically for efficient use with suppressors.