While these in-ear amplifiers were a good build and condition, there were issues. Putting them in resulted in loud feedback (howling) which was painful and potentially damaging. Taking them out was a fumble as there's no 'pin' so you need fingernails. The main issue was sound quality which was not suitable for me. The device seals the ear so there's no natural ambient sound, resulting in a very digital tone quality. Return was to China, so I took the offer of a £20 refund.