Flat rivets are a great alternative for securing the back strap on the medial side (inside) of the boot, especially if your horse has a narrow gait and tends to brush one hoof against the other.
In these cases, using flat rivets can help prevent the back straps from coming undone - something that can occasionally happen with Classic ball rivets.
For a more secure and streamlined fit, the back strap can be attached using flat rivets, and any excess strap beyond the rivet should then be trimmed off.
Just keep in mind that once flat rivets are installed, they’re not as quick to remove: you’ll need a screwdriver to take them off.
So it's best to double-check the fit before finalising the attachment. Flat rivets are not included with complete Flex Boots, but they are available for purchase separately. They are one-size-fits-all and suitable for all Flex Boot sizes.