Abstract: A disposable cop is disclosed, made of plastic material, and consisting essentially of a cropped cylindrical body, hollow inside, and having from 12 to 20 longitudinal reinforcing ribs disposed around the inside circumference, and arranged substantially radially at a uniform distance from each other and widened for a short distance in the section above their middle part, said longitudinal reinforcing ribs being:A. differentially and partially chamfered at the base of the cop, so as to provide inside the cylinder and with their free ends, a solid body or region having generating lines parallel to those of the cylinder, with an axial depth of about 12 mm and a cross-section which is a substantially equilateral triangle having radiused vertices, corresponding to the triangular entrainer of the spindle as required by ISO standards, andB. shorter by about 6 mm with respect to the total length of the cylinder at the head of the cop.