JBL Syncros S400BT: Close to Syncros-nicity | Sound & Vision
Amazon.com: SCOVEE USB to 2.5mm Male AUX Audio Jack Charging Cable for JBL Synchros S300 S300I S300a S400BT J56BT E40BT E30 E40 E50BT S500 S700 Headphones Stereo Power Wire for JBL Charger
JBL Synchros S400BT review | TechRadar
USB to 2.5mm Headphone Charger Cable for JBL Synchros S400 S500 S700 J56BT | eBay