Felting needles come as single-reduced (A) or double-reduced (B) types.

The most commonly used diameter for the shank is 1.83 mm (15-gauge). It is determined by the diameter of the needle-board holes. The intermediate shank diameter of the double-reduced needle is 1.20 mm (18-gauge) and 1.50 mm (16-gauge). The intermediate blade is necessary when the working blade is thinner, as it makes the needle more flexible.

KOPTEX offers two standard needle lengths: 3-inch needles (76.2 mm) and 3.5-inch needles (88.9 mm). The needle length is measured from the point to the inner edge of the needle crank.