The blue version of the JBL Synchros E40BT Bluetooth On-Ear Headphones feature a USB-rechargeable lithium-ion battery that provides 16 hours of music playback and up to 24 hours of talk time using the built-in microphone. If the battery runs out, a straight AUX cable can be connected to the headphones for wired operation. The headphones feature JBL's Pure Konnexx echo cancellation to reduce background noise and improve the clarity of your music or phone call. The built-in Bluetooth receiver includes JBL's ShareMe technology that allows the audio signal to be re-transmitted and shared by a second set of JBL ShareMe Bluetooth-enabled headphones.
The headphones utilize 40mm drivers to deliver a frequency response of 20 to 22,000 Hz into a 32Ω load. The headband is ergonomically designed to conform to the head with leatherette earpads, and the earcups feature a 2-point swiveling hinge, which enables folding them for storage and one-ear operation while DJing.