Swivels corkscrew size 6/0; the corkscrew bucktail fastener is designed for quick and easy leader and rig changes without tying. Assembled with a crane swivel for maximum protection against twisted and tangled lines, this swivel is a must for big game fishing.; swivels/rings/snaps ; Danielson; designed for quick and easy leader and right changes maximum protection against twisted and tangled lines a must for big game fishing.