Twisted-wire construction with 1/4″ hex shank in 25, 30, 35 and 40mm diameter.; Features and Benefits: 1/4″ hex drive, 3 1/2″ overall length; Unique large sizes for use on cars, trucks, motorcycles, engines, transmissions, etc.; Do not exceed 600 rpm; Includes: (4) Stainless Steel Brushes (#8037-254 – 25mm, #8037-304 – 30mm, #8037-354 – 35mm, #8037-404 – 40mm)