It would not be expensive for the supplier to have heavy duty stainless steel screws included in his set but they decided to go with standard carbon steel. These are great for voice calls and uses as noted above in the Pros section. Milk, sweat, etc still wasnt going through. The sandals fit longer, which is good for narrow footers. The soles are very comfortable and easy for me to walk in. Bummed for the cost I have to constantly fix these shoes. They are so easy and they fit super well. I went down a half size as recommended and they just barely fit so be aware of that. Between the two issues, and with a heavy sigh, I returned them. These recent additions are truly amazing.