On the Q-series, M-series, S-series and the V4pro rechargeable the exact model name is either engraved or printed on the product itself.
With the V3air, V3air rechargeable, V3pro and V3pro rechargeable you must look for these identifiers:
V3air and V3air rechargeable
Is the headband black with blue accents? Then your headlamp is either a V3air or V3air rechargeable.
Does your headlamp use alkaline batteries? then it is a V3air.
Does your headlamp use a rechargeable battery? Then it is a V3air rechargeable
V3pro and V3pro rechargeable
Is the headband black with yellow accents? Then your headlamp is either a V3pro or V3pro rechargeable.
Does your headlamp use alkaline batteries? then it is a V3pro.
Does your headlamp use a rechargeable battery? Then it is a V3pro rechargeable