6 different powers available.#4 (Silver) is the weakest & #9 (Orange) is the strongest.May be purchased separately or in a kit.1/8″ & smaller Verifiers can be used with either our Standard Size Peep Housing, or our Large Peep Housings with the use of a Reducer.Large Verifiers are for use with our Large Peep Housings.5/16″ XL Verifiers are for use with our 5/16″ XL Peep Housing.