I purchased them for $4,000 at Technopark and replaced them with the JBL 450BT. From experts: 1) Daylong battery life; 2) Rechargeable; 3) There will be a brief and quiet signal if the ears are sitting down, as opposed to the loud and prolonged JBL sound that reminds you to charge them for three hours every ten minutes. 4) They effectively transfer the signal; the sound can be heard clearly even in the adjacent room (I use BT 5.0). 5) Because ear pads don't exert pressure on your ear, ears don't feel weary. 6) Effective sound absorption I'm quite happy with the purchase. a really cozy headset with good sound. Even at their current price of $8,000, they are unquestionably worth the money.