Y-Thread Cask Connection Nut
Y-Thread Square Cask Nut
Y-Thread Cask Connection Square Nut ??A/F (for use with ??mm spanner)
For use with Y or L Cask Barbed Tails.
Y-Thread is an old brewery thread (Yorkshire Thread) still used by the likes of Samuel Smiths Brewery, Everards Brewery and JW Lees ++