Tiger Rock Six Position Mil-Spec Buffer Tube Kit AR-15 M4 Blue Small. The Buffer Tube is constructed of 6061 T6 Aluminum and is durable and weather-resistant. Specifications for Tiger Rock AR-15 M4 Six Position Mil-Spec Buffer Tube Kit: Manufacturer: Tiger Rock Fabric/Material: 6061-T6 Aluminum Gun Make: AR Platform Gun Model: M4 AR-15 Package Contents: Tiger Rock AR-15 M4 Six Position Mil-Spec Buffer Tube Kit AR-15 Stock Buffer Tube -Mil-Spec AR-15 Buffer Castle Nut Stock Buffer End Plate AR-15 Carbine Length Buffer Spring - Steel AR-15 Collapsible Stock Buffer -3.0 Oz-Carbine Length What firearm models does the manufacturer say Tiger Rock AR-15 M4 Six Position Mil-Spec Buffer Tube Kit is compatible with? The manufacturer says that Tiger Rock AR-15 M4 Six Position Mil-Spec Buffer Tube Kit is compatible with AR-15 M4Tiger Rock ST007MBL: Six Position Mil-Spec Buffer Tube Kit AR-15 M4 Blue Small