Aero Precision .30 Caliber Crush Washer Black. It is not necessary to be purchased separately. This individual product is available for customers who have lost or damaged their existing crush washer. Specifications for Aero Precision .30 Caliber Crush Washer: Manufacturer: Aero Precision Gun Model: M5 Condition: New Fabric/Material: Steel Projectile Caliber: .30 Caliber Finish: Bead Blasted Country of Origin: USA Package Contents: Aero Precision .30 Caliber Crush Washer What firearm models does the manufacturer say Aero Precision .30 Caliber Crush Washer is compatible with? The manufacturer says that Aero Precision .30 Caliber Crush Washer is compatible with M5Aero Precision APRH100076C: .30 Caliber Crush Washer Black