The Attachment Kit (AK) is both a Rivet Kit (RK) and a Hole Punch (HP). The RK is use mostly for sandals and some shoes that don't have eye holes to attach the brace or are made with more of woven material where the hole could stretch out. Some sandals have strap that crosses the foot on an angle so the RK has various chain link lengths to offset the angle of the sandal to keep the brace straps at an equal tension. The hole punch is use to make holes for the rivets or it can be used to simply punch a hole in any shoe to use instead of a RK or eye hole for a more precise tension fit for the brace - this is my preferred way to attach my braces to my shoes. I find it just fits easier and more precisely than eye holes, although eye holes work just fine for the most part. This item is Refundable.