Harrows Supergrip Spin Nylon Shafts. The 21st century nylon shafts, features precision factory fitted, machined rings which, unlike traditional springs do notopen when flights are fitted. This results in an incredible vice-like grip. Length: 35mm; (does not include thread – 5mm) Thread: 2baHarrows Supergrip Spin Nylon Shafts. The 21st century nylon shafts, features precision factory fitted, machined rings which, unlike traditional springs do notopen when flights are fitted. This results in an incredible vice-like grip. Length: 45mm; (does not include thread – 5mm) Thread: 2ba Harrows Supergrip Spin Stems – Dart Shafts – Smokey