Slippers by their nature do not fit in a way that supports the foot. I have worked out at 100s of gym over the years and now with COVID-19 and all professional fitness clubs/gyms shut down, Ive had to build my own home gym. Input microphones are covered in a felt that protrudes past the plane of the earpiece, could get snagged and will certainly collect dust if out in the wild. I have listen to recordings I thought I knew well and yet these IEMs have opened up a new level of detail I didnt realise existed. When it comes to value for money and if you are into running on firm ground or astro then this is a must purchase. I especially like that they fit over the ear rather than just sitting on the ear. Es para tenis, pero es para un profesional, es muy muy grande, le caben como 3 raquetas. The only problem that I had, however, was that when I received the phone the shipping box wasnt packed properly and when I opened the box, the phone was laying outside of its box and so were most of the accessories that it came with! I am a 40 UK (9) but ordered the 39. These are my wedding shoes.