The strength is increased about 10% more han ST-66 beacuse the wire features TAFF WIRE. STX-68 can make lure action as same with ST-66 though STX-68 is stronger than ST-66. The STX-68's are perfect for large surface poppers, trolling baits, and jigs. They are a true triangular monster and is a great choice for upgrading any sea fishing lure.