Round laces in the diameters 1.5 mm, 2 mm, 2.5 mm and 4 mm.
Round laces are often used in all lace-up shoes. Whether as a replacement for worn shoe laces or as accessories to set accents through the choice of colour.
For concealed eyelets the two thinner ones are best suited. If you have more robust footwear, then the 2.5 mm diameters are often just right. Attached eyelets should have an inner diameter of 3-4 mm so that the lace can slide easily. This avoids unnecessary wear.
Always the right laces.