My most recent wired Ultimate Ears in ear monitors packed in so I started using the Cardo speakers in my lid, with filtered ear plugs. I remembered I had an older set of U/E’s that were different, in that they fed the sound through tubes into the ear moulds. They had stopped working because several long trips in high temperatures had softened the link tubes which kinked, and blocked the sound. So I found a supplier of tubing, from China, at only about £2.50 per metre delivered. Now working perfectly again.
