I use the outdoor tech wireless chips 2.0. Obviously not really designed for bike helmets but oh well. Not really anything crazy but saved me a ton of money while allowing the possibility for phone calls and music inside my helmet.
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Just took these, some double sided tape and stuck them in the ear wells. The only buttons are on the outer sides so to click them i either do so while the helmet is off pushing the device against the side, or reach up and in while its on. Does the trick for me