Cables:

• On the packaging
• Or the sticker on the cable

Earpads:

• On the packaging

Speaker units:

• On the packaging
• Or on the right speaker unit with an NFC reader application (e.g. GoToTags, NFC reader)

Headbands:

• On the packing 
• Or the sticker on the cable 
• Or on the top inner side of the headband with an NFC reader application (e.g. GoToTags, NFC reader)