Flex boot include 5 ball rivets that are part of the fastening system. Rivets are attached to the screws that have washers under them.
The strap that goes around the pastern (FlexGaiter TPU), has one rivet. The shell of the boot has 2 rivets per side.
We recommend that you check the rivets from time to time to make sure they are not loose.
If your horse has a narrow gait and she is damaging the ball rivets, back strap or the boot it self inside the foot, we recommend installing flat rivets inside the foot.