These skirt layers are from a couple sources. The layers with numbers in the 500 and 700 series have 20 strands and the 600 series have 700 strands.
Silicone layers are great for making up your own combination of colors and skirt stands. Some guys like a few strands for a lighter feathery fall and some like 60 strands or more for a heavy mop type jig that falls faster. Color combinations are endless!!!!