Yosoo 950pcs 0.6mm Dia Round O Ring Watch Case Back Gasket Size from 12mm to 30mm This is a set of 950pcs. new o-rings gaskets Use for watch repair and must have a watch maker all sizes The o-rings different 19 sizes thickness 0.6mm 19 different sizes from 12 to 30 mm: 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27,