Aero Precision M5 Complete Upper, 308 Winchester, 16 Barrel, 1:10 Twist, Rifle Length Gas System, ATLAS S-ONE Handguard, Anodized Finish, Black, Does Not Include BCG or Charging Handle APAR538705M22 The M5 308 come with the S-ONE line of handguards which is designed with size and weight in mind" providing the perfect addition to your lightweight build. The proprietary ATLAS attachment system is a durable and dependable mounting platform" maintaining a slim profile while still providing the strength and stability customers have grown to love from Aero Precision handguards.