The Sig M400 Tread and Riflescope package includes a factory mounted 3.5-10X42mm Sierra3 BDX riflescope with 8 on board Smart BDCS. The Tread features a free floating M-LOK handguard, mid-length gas system, ambidextrous controls, Sig enhanced trigger, 6-position SL-K stock and a black polymer grip. The Sierra3 BDX is mounted with Alpha rings.