Shoof's self-piercing 8mm brass bull rings have a durable thumb-screw lock & screw-driver slot. Three sizes available: small 64mm, medium 70mm, large 80mm o.d. NB: Brass rings are more durable than copper.
Shoof own-brand self-piercing brass bull rings. Thumb-screw type locking pin, broken off when tight, revealing screw-driver slot. Dimensions are o.d. in mm.
NB: Brass rings are harder wearing than copper rings.
