Brush material and size: Steel, brass, nylon – 6.35, 9.5, 12.7, 15.9, 19 and 25.4mm. Each brush has 1/4″ hex drive shank. Quick release screwdriver with comfortable handle. Also includes 6″ extension with quick release chuck. Suitable for numerous uses including removing carbon cleaning from internal threads or pipes and cleaning drilled holes. Similar Items: F3610, F3600.