You may select either a leather or a metal strapkeeper for your collar. This part is pretty self-explanatory and based on personal aesthetic preference. Cat Collars or any collar tapered to 1/2-inch at the buckle will not have strapkeepers.
Dog collars for necks less than or equal to 12" will have a "stacked" strapkeeper and d-ring, meaning that there will not be a chicago screw separating them, as shown in the photo at the top of the page. This is to help maximize the design area for smaller necks.