Simply snaps onto the under side of a #30 narrow blade set on your small clipper. Assures that hair is all clipped to one length. The steel composition offers snag free tips to allow the hair to ?ow through easily. Does not ?t on the wide blades that are commonly used on small clippers, example: Andis Super Blocking Blade. A narrow blade set must be used. Guide thickness: 1/8", 1/4", 3/8", 1/2", 5/8", 3/4", 7/8", 1". Sold as set.