PFERD Stem mounted knot power wire end brush for heavy-duty and severe applications, recessed areas and corners such as weld and mold cleaning. Suitable tool drives: straight grinders, flexible shafts. Recommended for use on variable speed tools. Available with coated cup to prevent damage to work piece. Specification: Diameter (inches): 1; 1/4" Shank; Wire Size: .014; Filament Material: Carbon Steel Wire; Maximum Rotational Speed (RPM): 20000; Trim Length (inches): 1.