5 or 10 in most shoes and based on reviews I went with a 9. It is backwards. If you wait a while looking for a spot the adhesion dries so make sure you know where u want tht I am disabled and cant have any materials on my skin but these dont hurt. These shoes are the best shoes I have ever seen. Overall the installation took about 1 1/2 hours. They were still there and werent damaged, so I guess whoever decided they may want to steal them subsequently decided they werent what they were looking for. This piece was an amazing addition to the home gym. Initially- I thought the shoes were too small (based on my heel right at the end). The young is not adjustable but that doesn?t bother me.