Berkley Vanish Fluorocarbon Line is the most flexible, easiest casting fluorocarbon on the market today. Vanish 100% fluorocarbon has a similar refractive index to water, so fish can't see it. This Vanish Fluorocarbon Line features an improved formula, with 20% better shock strength and improved knot strength. This newer, more flexible formula makes this line much easier to handle than the 1st generation Vanish line. Fluorocarbon line is non-absorbing and maintains strength and abrasion resistance underwater.