a. Samkvæmt stærð hnappsins (þ.e. stærð þvermálsins)
That is, we often say 14, 16, 18, 20, 60 and so on! Its conversion formula is: diameter = model 0.635 (mm). If we have a button in our hand, but don't know its size, we can use a caliper to measure its diameter (mm) and divide it by 0.635.
b. Það er önnur leið til að tjá stærð hnappsins, nefnilega L
