Spectra fiber braided fishing lines have gained wide-spread acceptance in the last few years because:
Low Stretch
Spectra has very low-stretch (3% maximum) which means a fish bite is easily felt and the hook-set is quick and sure. Getting a fish away from the bottom structure is more likely, compared to monofilament stretching more than 25%.
Small Diameter
A very high strength-to-diameter ratio of Spectra is attractive because:
More line can be put on a given reel.
Smaller reels may be used in a given application.
Greater breaking strength line may be spooled on the same reel.
High Tensile Strength
Spectra fiber is so strong that it is used in bulletproof vests; replacing Kevlar in that application. It is about 10 times as strong as steel, pound for pound. The finished line has a tensile strength of about 600,000 pounds per square inch versus monofilament which has a tensile strength of about 100,000 pounds per square inch.
Long Life
Spectra has a very long life, it does not rot, and is not readily damaged by ultraviolet rays in sunlight, as is monofilament.
Not Effected by Water Spectra does not swell in water, nor does it lose strength when wet.
Light Weight
Spectra does not weigh you down. Stand-up fishermen really appreciate the lightweight of a spool of Spectra
Spectra: 
