Ergonomic Design - The shape of k2S perfectly fits the curve of inner contour of ear. With round soft silicone ear tips, it can offer more wearing stability and comfort when in use. Whether you' re running or jumping, the earbuds will stay in ear secAdvanced Bluetooth 5.1 Technology - Support HSP, HFP, A2DP, AVRCP. Provides in-call stereo sound. Greatly improve the transmission speed and providing you with a low-latency listening experience.Hi-FI Stereo Sound Quality - K2S acoustic experts focus on precise acoustic tuning and find out the best sound characteristics for human hearing sensitivity. Accurately adjust every detail to achieve a perfect balance of bass, midrange and treble.Dual Purpose Charging Case And Power Bank - The charging case can also be used as a power bank to charge your phone when you are on the go.