These ultra fine pins were created to meet the most exacting needs in sewing, quilting and embroidery works. Their .40mm narrow shaft is perfect to use on cotton fabrics, fine silk, waste silk, and batik with tight weft, and are the best things we've found for our tightly woven Microduoplex. These pins make pinning our strong and supportive Microduoplex as easy as pinning any other fabric. Glass pin heads are orange and blue, and won't melt with ironing. These are non-magnetic pins, and will not be magnetized on a magnetic pin cushion.