A Extended Ribbed Mayfly Body With Adjustable Tubing 

It’s a standard tube for tying. You can look up products from wapsi, and others. This particular one came from “spirit river” but I don’t think they are in business anymore. “Larva lace” is another you can check. For a standard size 12 pattern medium is the size you want. You can get smaller tube but it becomes increasingly difficult to work with. And there is are , honestly better options. Thanks for your comment

Great video . Thank you . Looking forward to seeing more helpful videos from you . B