[ HAPPY CUSTOMERS ] : We are committed to serving customers with reliable quality products , LORELEI continues to deliver the best user experience with innovative technology from a trusted brand . Please feel free to contact us if you have any request , we will solve your problem within 24 hours. [ Bluetooth 5.3 & Built-in Mic ] : Two 40mm driving units , Bluetooth 5.3 chip , audio transmission speed is more stable , lower delay , bring you wonderful music enjoyment. Lightweight headphones with a built-in microphone make calls as clear as if you were talking face to face. [ Delivers deep bass audio ] : Dual 40mm HD high resolution audio drivers, high response diaphragm, lightweight voice coil. Delivers unparalleled sound without interruption. High quality sound just needs to be heard. Let it find the rhythm of your soul. [ Unique lightweight ergonomic design ] : Professional-grade protein ear pads that rotate inward at 100° and fold inward at 120° make the earmuff extremely light , which allows you to use for a long time with maximum comfort . Ergonomic headphone construction, multi-level adjustable headband can be obtained to suit your best size. [ 50 Hours Music Enjoyment ] : A built-in 500mAh battery won't allow your headphones power off. Just a single charge,you can enjoy your world reduce noise for 50 hours' long time . Or plug in 3.5mm stereo audio cable to prolong using time when battery is low.