Magnetic capping head clutch, compatible with machinery for applying 15-43 mm screw-on caps, has hysteresis designed for smooth performance. Repeatable to within ±2%, it uses Vernier scale for adjustable torque settings from 2-24 lb-in. It also incorporates various sizes of input and output shafts; 3 in. dia common magnetic component made from anodized aluminum or stainless steel; and chuck output adapters. Absence of contacting parts reduces maintenance.