The date code of the Mirage family of headsets will be located on the side of the headset, near the speaker. The first two numbers represent the month (01=January, 02=February…). The two numbers following the dash represent the year (04=2004). Next is the model of the headset. An “H4” represents the Mirage H41 model. If an “N” is present, the headset is a noise-canceling model. If an “R” is present, the headset has been re-manufactured or replaced by Plantronics. Any trailing characters are used by Plantronics for coding purposes.