1.UL certificate 2.ISO 9001:2008 3.GB/T 19001-2008 QC-L:Low side,connection 1/4" MaleQC-H:High side,connection 1/4" Male QC-15AL: Low side,90° R134A Quick Coupler, connection 1/4" MaleQC-15AH: High side,90° R134A Quick Coupler, connection 1/4" Male Quick Couplers