I thought I should use it together with a jet type helmet, but it was a failure. First of all, there was no indication of the size, but because it is a cheap product, I thought that if it was useless I would use it for maintenance work. However, it was smaller than I imagined, so I could not use it on my glasses .... You may as well buy this kind of goods after seeing it again. I will give it to acquaintance who does not wear glasses. Although there are no problems with the product itself, there may be people who have a strange impression beyond imagination.