AIM Sports Inc M4 Style 6 Pos Collapsible Stock - Mil-Spec Black Medium. Aim Sports 6-Position AR/M4 stock is a complete stock assembly with commercial carbine buffer tube spring buffer USGI compatible stock with QD swivel cup ambidextrous sling mount end plate.image Specifications for AIM Sports Inc M4 Style 6 Pos Collapsible Stock: Manufacturer: AIM Sports Inc Color: Black Gun Model: M4 AR-15 Gun Type: Rifle Included Accessories: Standard Condition: New Hand: Ambidextrous Fabric/Material: Aluminum Polymer Package Contents: AIM Sports Inc M4 Style 6 Pos Collapsible Stock What firearm models does the manufacturer say AIM Sports Inc M4 Style 6 Pos Collapsible Stock is compatible with? The manufacturer says that AIM Sports Inc M4 Style 6 Pos Collapsible Stock is compatible with AR-15 M4AIM Sports Inc ARSTKC-C: M4 Style 6 Pos Collapsible Stock - Mil-Spec Black Medium