Fiberific! String Theory is 100% pure silk filament 25km per 100g, that is not a typo. This silk is 2-3 strands reeled from cocoons, given a slight twist and bleached. String Theory is perfect for plying! On occasion, I reel 5g/1250m bobbins. They will not always be available, but if you want one, email me on firstname.lastname@example.org. I will put you on the wait list.