That's a **ferrite bead** (EMI choke) on the DC cable.
It suppresses high-frequency electromagnetic interference (noise) generated by the charger's switching circuitry. Without it, the cable could act like an antenna, radiating interference that might affect nearby electronics, Wi-Fi, or cause the laptop to fail EMC regulations.
Common on quality laptop chargers.
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16
128g-N875,000
256g-N950,000
16 plus
128g- N900,000
256g-N1,100,000
512g-N1,200,000
16 pro
128g-N1,050,000
256g-N1,150,000
16 pro max
256g-N1,350,000
512g-1,450,000