Studs are small charms that simply pop into the holes of your smartwatch bands for a snug fit.  

sport bands from Apple

• Our Apple Watch studs fit all sizes of Sport bands from Apple (38mm, 40mm, 42mm, 44mm) 
• Make sure the holes where you place your studs do not have band overlap behind them. This will ensure that the studs are securely in place. An extra layer of band could push on the back of the stud and cause it to pop out. This overlap may happen if you have very small wrists.

third party bands

• The holes in some third party sport bands may be a different size than the holes in Apple sport bands. Make sure your stud fits securely if you have a non-Apple branded sport band.
• We are not able to guarantee fit or warranty our studs on third party bands because even if they look just like Apple Sport bands; the material of the band and size of the hole may vary and affect how securely the stud fits. 

 classic and infinity bands from Fitbit

• Our Apple Watch studs also fit older model Fitbit Alta & Alta HR Classic bands with round holes
• Newer bands from Fitbit have rectangular holes. We have a collection of styles that are designed with rectangular backs to fit in Classic and Infinity bands from Fitbit bands. Browse that collection here. (ADD URL)