No way to know how long you will be able to get out of an attachment until you get your first unit and start experimenting with different attachments. During my first few years of wearing I was only able to get 4 days out of an attachment due to adhesive breakdown and irritation issues. I eventually got tired of having to remove after only 4 days so I decided to try some new attachment methods and supplies, which paid off because I am now able to get a solid week out of my attachments, even with sweating at the gym a few days per week.