Tetra - Nylon Brush .12GBrass Core - SKU: TF1054Product Description:Nylon will not harm your barrel. Tightly wound precision brass core brushes effectively remove fouling from gun barrels. Industry standard 8-32 male thread (5-40 for .17 Cal. & .204 Cal.) 5/16-27 male thread (12,20,28 & 410 Gauge) Close tolerance specifications for perfect bore fit Will not harm or scratch steel Durable and reusable