Explain metal locking

"Meet Varni B580 Bluetooth neckband, that’s all about power. It features 35-hour playtime with InstachargeTM technology that delivers 35 hours of music in just 1hours of charge. The 10mm speaker driver offers loud and clear sound no matter your surroundings while the call alert ensures that you are always in loop even in the midst of everything. Want to get your work done? Just command your preferred assistant and it will be done. The IPX5 water-resistant rating takes care of the sweat while you push yourself. Available in attractive colours, with Varni, you are spoilt for choice. •Premium Metal Earbuds, Flexsoft Neckband. Charging Time:1.5hrs •35 Hours Music Playtime Under Optimum Audio Settings •Dual Equalizer Modes for Normal & Deep Bass output •Connect to your media devices instantly, take the advantage of dual pairing and enjoy real-time audio with Bluetooth v5.0 •Command your playback, hands-free and activate smart voice assistant easily via its smooth integrated controls •Wireless Neckband; Magnetic Locking Earbuds; Lightweight Design for Comfort; IPX5 Sweat/Water-resistance; Skin-friendly Material; In-line Remote Control to Manage Music & Call"