If you lose one of the Airpods, the model of one left in your hand is A2032. AirPods (1st Gen): A1523(Right side), A1722(Left side). AirPods (2nd Gen): A2032(Right side), A2031(Left side). The 2nd Generation AirPod Models A2031 & A2032 will only work with eachother and will not work with Left or Right 1st generation, but you can use 2nd Gen. Left & Right AirPods in either a 1st or 2nd Gen Charging Case.
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