[ADD-ON HEADPHONES FOR OPERA PLUS] The AS90K is intended as add-on headphones for the Avantree Opera Plus TV watching set. Please note that it does NOT include a charging dock and it is NOT compatible with the Opera. [CLEAR VOICE MODE] The AS90Ks clear voice EQ mode boosts on-screen voices so you can hear dialogue more clearly & easily. [CINEMA SOUND MODE] Immerse yourself in a cinematic sound experience with the cinema sound EQ modes dynamic, spatial sound enhancements. [NO LIP-SYNC DELAYS] Enjoy perfectly synced visual & audio when connecting to your TV via the Opera Plus transmitter. [EXTENDED COMFORT & PLAYTIME] A playtime of up to 20 hours provides enough battery life to last through multiple movie marathons, while a lightweight design & plush components guarantee comfort throughout.