A disc of a diameter of approximately 580 mm and a thickness of approximately 3 mm, consisting of 2 layers made of polyurethane, one of which has machined grooves, whereas the other has an adhesive coating protected by a detachable plastic sheet (so-called ‘polymeric pad’).
Umbes 580 mm läbimõõduga ja umbes 3 mm paksune ketas, mis koosneb kahest polüuretaankihist, millest ühel on töödeldud vaod ja teisel eemaldatava kilega kaitstud liimikiht (nn polümeersilur).