1) screen goes all white some time during the call. Regardless of how long they last, I will continue to purchase them again. There is no way to tighten them as the sandal straps are not adjustable. Third, most digital pianos have headphone jacks with high output impedance. Also, works great with the iPhone XS. As well as an extra button its not supposed to have. Id say if youre between sizes, like me, consider going larger, rather than smaller. Everything about the phone from calls/text to media player and video games run super smooth with no hiccups. i ordered the 14 for my son and they are more like a 12 . There is not a significant amount of arch support.