Close tolerance fit for cleaning patches provides maximum cleaning power and versatility. Accomodates all Prosmith cleaning rods - standard threading 8/32 (different for shotgun, and 17). Machined from durable high quality brass. Best design. Great value. All calibers. Thread SizingIndustry Standard 8-32 male thread (5-40 for .17 Cal. & .204 Cal.)5/16-27 male thread (12, 20, 28, & 410 Gauge)