The M400-SDI X was designed to meet the highest standards of performance and reliability. From the rifle's full suite of ambidextrous controls to its proven mid-length gas system. Features fully Ambi Controls- safety, charging handle, bolt Catch & mag release; 2-Stage Matchlite Duo trigger; free floating M-LOK; mid-length direct impingement operating system and 6 position Magpul SL stock.
| Manufacturer | Sig Sauer |
| Model | M400 SDI XSeries |
| Caliber | 5.56 NATO / 223 Rem |
| Type | Rifle |
| Capacity | 30+1 |