Product name :Pearl Purl 

Pearl Purl is a goldwork wire with the appearance of a row of tiny metal pearls.  It is made of a coil of wire so there is a hole through the centre.  It is very strong and easy to manipulate while stitching and adds texture to your embroidery.

Use Pearl Purl by invisibly couching over it, letting a matching thread slip between the coils.  The thread will need a good coat of beeswax.