EC 0, fit for 0.75mm(sq) to 1.5 mm(sq) EC 1, fit for 0.75mm(sq) to 3. ... 5 mm(sq) EC 2, fit for 3.5mm(sq) to 8.0mm(sq) EC 3, f Our factory ... custom marker number, like spanish marker, russia marker, etc...EC 0, fit for 0.75mm(sq) to 1.5 ... .75mm(sq) to 3.5 mm(sq) EC 2, fit for 3.5mm(sq) to 8.0mm(sq) EC 3, fit for 5 ... .2mm(sq) to 10.0mm(sq) EC ...