CMMG ZEROED Polymer Ejection Port Cover AR15. Specifications for CMMG ZEROEDAR-15 Polymer Ejection Port Cover: Manufacturer: CMMG Gun Model: AR-15 Fabric/Material: Polymer Package Contents: CMMG ZEROEDAR-15 Polymer Ejection Port Cover What firearm models does the manufacturer say CMMG ZEROEDAR-15 Polymer Ejection Port Cover is compatible with? The manufacturer suggests that CMMG ZEROEDAR-15 Polymer Ejection Port Cover is compatible with AR-15CMMG 55BA5CD: ZEROED Polymer Ejection Port Cover AR15