In the box there is a warranty card for a 2-year warranty from the manufacturer with a serial number. The sound quality is not as good, but this is normal considering the features of the headphones. As already mentioned at high volume, everything (everyone) is heard, so the drivers will "tickle" your ears. The headphones do not turn off themselves after a long period of inactivity, but I'm not sure if this affects the charge level. For my purposes I'm happy with my purchase.
Headphones Sennheiser CX 300-II, black
318 Review
Huawei Freebuds Pro MermaidTWS with Active Noise Cancellation - Silver Frost
299 Review
🎧 Huawei FreeBuds Pro Earbuds with Advanced Noise Cancellation, Bluetooth 5.2, and 3-Mic System for iOS and Android (Carbon Black)
295 Review
🔴 Sleek Mystic Red Samsung Galaxy Buds Live with Active Noise Cancelling - Wireless Earbuds
274 Review
Panasonic RP-HS46 Slim Clip-Type Earphones in White: Quality Sound On-the-Go
76 Review
New White Marshall Minor II In-Ear Bluetooth Headphone
101 Review
🎧 Experience Unmatched Audio Quality with Marshall Major 4 Bluetooth Headphones
104 Review
Massdrop x Koss Porta Pro X On-Ear Headphones: 🎧 Noise-Cancelling Mic, Voice Assistant, Track Skip | Collapsible Midnight Blue
314 Review