AK-351 speakers audio system sound portable mini bt wireless speaker Description Feature: 1. If there are two speakers that can be connected in series, they will be played synchronously after connection, which has a stereoscopic effect. 2. The included shoulder strap can be used during outdoor sports and is easy to carry. 3. HiFi grade sound, surround sound, high resolution, bring you a high‑fidelity sound music experience. 4. Compatible with devices such as mobile phones, computers, tablets, and other operating systems such as for /Android/iOS. 5. 5.0 high‑performance chip, intelligent automatic pairing, while reducing power consumption, greatly improving the transmission rate. Specification: Item Type: Speaker Material: ABS Color: Black Version: V5.0 Support Agreement: A2DP HSP HFP AVRCP Signal Transmission Range: About 10m Frequency Response Range: 100Hz-18KHz Speaker Specifications: ∅57mmx2 4Ω/5W Battery Specification: Lithium battery 3.7V/1200mAh (built-in) Music Playback Time: About 3 hours Signal to Noise Ratio: ≥90db Distortion Rate: 1% Charging Interface: Micro Input Specifications: DC 5V—1A Charging Time: About 2 hours Function: /1+1 couplet, USB/memory card, FM, AUX hands-free call, mobile phone holder, with colorful lights