I've posted this deal before when it was £4.99 for prime users but then the price went up to £9.99 its now back at £4.99.
Anti-static-interference Hands-free Talking
• Drive safely and legally, supports hands-free phone conversation through the car stereo with Anti-static-interference clear sound. Don't worry about the beep sound before answering phone calls. Long Life Span & Optimized Stability
• Adopt SMD crystal material, longer life span and optimized stability than other similar products.
• Built-in rechargeable battery compared to others will save you money on buying batteries. Small, Compact, Lightweight & Easy Tuning
• It is small, compact and lightweight, easy to tuning with easy touch forward and backward buttons.