Purchased in July 2023. The serial number on the outer box is handwritten on the back of the paper. I bought these mainly for home use, but I'm selling them because I found another pair of earphones sufficient. I think I haven't used them very often. Please refrain from purchasing if you are concerned. The original charging cable is not included, so please purchase a TYPE-C charging cable for use. Although I have initialized them, please initialize them yourself before use. I will wipe them with a disinfectant wipe before packing. I will also take waterproof measures and pack them in simple packaging. Recently, there have been increasing reports of damage, so to prevent trouble (swapping), I will take photos of the model number, etc., at the time of shipment. [Items to be packed] Main unit: WF-1000XM4 Accessories (earphone tips, warranty, instruction manual, etc.) *Charging cable is not included Outer box, paper from the outer box Wireless Noise Canceling Stereo Headset WF-1000XM4 (B) Black Brand: SONY Wearing style: Separate left and right, completely independent Earphone/Headphone type: Canal type Wireless/Wired connection: Wireless Earphone/Headphone functions: Noise canceling, Hi-Res, Microphone, Ambient sound, Waterproof, splash-proof, Remote control Wireless function: Multi-pairing Bluetooth codec: LDAC, AAC, SBC IP standard (waterproof standard): IPX4 Drive method: Dynamic type Driver size (mm): 6.0 mm Charging terminal: USB Type-C Charging time: 1.5 hours Weight (g): 14.6 g #SONY #Sony #WirelessEarphones #Bluetooth #Black #Beautiful #HiRes #Earphones #Black #sony #NoiseCanceling Other features: Noise canceling, Hi-Res compatible