3.7 V 750 mAh Li-ion Battery for Bose QuietComfort 35 II Wireless Bluetooth Headphones QC35 and Sony WF-1000xM3 Charging Case Battery Upgrade

Unfortunately I never received them. Someone open my parcel and stole the battery but a friend of mine bought the same for his headphone and this was his experience:"My headphones battery died and I was looking to find a replacement.Out of warranty Bose only offer me to buy a new headphones so i decided to repair them by myself.I've read different review about this one saying that it wasn't going to feet inside the headphone... they were wrong. The battery fit perfectly and the headphone is alive again!The battery life is longer than the original one.Worth the money!"

Transferred the battery to my Bose qc35 headset and initially saw very little difference compared to the nearly 8 year old battery. Two weeks later my headset doesn't even turn on anymore and just shows a dead battery indicator. That's after charging for 2 days straight. Absolutely do not recommend.