A coated copper wire brush head that is used heated. Fit into the Stylus (older single heat type) and tighten the retaining side screw with a screwdriver. These metal fibres are fragile so be kind to them and do not “stab” into the wax colours. the fibres will bend if pressed too hard during use. they can easily be bent back. To clean use a cheap candle, fill the heated brush head with clear wax and pinch the fibres between a tissue. Always pull the tissue gently along the metal fibres from the Stylus unit towards the tip. Once tangled it is hard to repair!