Black Magic ?TWIN SPIN? ball bearing swivels have an exceptional rotational capacity generated via an innovative design that gives both welded rings the ability to rotate independently.Features:STRONG - Heavy duty brass swivel construction coupled with a high strength stainless steel coastlock snap provides the ultimate in swivel strength and performance.SMOOTH - Two rotating welded rings ensure that the swivel and coastlock snap will never twist and ?lock up? under load, this sometimes occurs with swivels with only one ring.BLACK - For a purpose, some fish species will strike at a shiny swivel while you are playing the big one.PROVEN - Bruce Martin (skipper of one of New Zealand?s premier game boats ?Predator?) trolled lures and livebaits for thousands of miles using our prototype ?twin spin? swivels with outstanding results numerous marlin, tuna and sharks were hooked with no line twist and no opened snaps.TESTED - As with all of our products these are batch tested to destruction in our lab.