Sennheiser PXC 550-II Wireless - NoiseGard Adaptive Noise Cancelling, Bluetooth Headphone with Touch Sensitive Control and 30-Hour Battery Life (508337) - Newegg.com
700mah 3.7v New Battery For Sennheiser Pxc 550 Bluetooth Headset Li-polymer Rechargeable Replacement Ahb413645pct Track Code - Digital Batteries - AliExpress
Sennheiser PXC 550 Wireless gaming headset audio quality, price, mic, and full specs review - GPUCheck United States / USA
Sennheiser PXC 550 Wireless review | TechRadar
I recently bought PXC 550 ii, this is the second time I charge it, it's been more than three hours already and the third led is still blinking (internet says full charge