5mm output. Also, not for narrow feet. I am sleeping better now and very pleased with these earphones. Product was better than expected. I have been using Aftershokz headphones for some time now after running with normal in ear headphones and nearly not hearing a car and nearly ending under it along a country lane so I carried out some research and found this company. Really temperamental in terms of pairing (always having to reconnect via bluetooth) and reliability - Full charge but the ear pods wont switch on half the time unless the jet stream is in a certain direction. If the bar holding the hooks was connected on the backside there would be enough room to sit. The only complaint I have is that all day comfort sole wears differently than the wobbleboard- but this shoe only comes with the all day comfort sole. They have a very balanced tone and they are comfortable . These shoes are not waterproof, and will sometimes slip on mud, wet leaves, wet rock, as the sole compound is fairly hard ( for wearability ), these are ultimately a good weather shoe.