Aero Precision SOLUS Small Caliber Bolt Head Parts Kit 223/5.56 NATO 300 BLK Black. Specifications for Aero Precision SOLUS Small Caliber Bolt Head Parts Kit: Manufacturer: Aero Precision Color: Black Action Type: Bolt Action Caliber: 5.56x45mm NATO .300 AAC Blackout .223 Remington Package Contents: Aero Precision SOLUS Small Caliber Bolt Head Parts Kit Small Extractor Extractor Detent (2x) Extractor Spring (2x) Ejector (2x) Ejector Spring (4x) Ejector Retaining Pin (2x) Bolt Head Pin (2x) O-ring Aero Precision APRH103346C: SOLUS Small Caliber Bolt Head Parts Kit 223/5.56 NATO 300 BLK Black