Made from nickel plated steel wire wrapped around tin plated hex shaped steel core wire. By far the most popular, produces well balanced all around good sound.  
 

D'Addario pioneered the use of nickel plated steel for electric guitar. Today, discerning professionals like Mark Tremonti, John Scofield, Carlos Santana, Pat Metheny, and Brad Delson, just to name a few, choose XLs for their distinctive bright sound and excellent intonation 

Martin Strings are high quality strings for daily use. . Martin Strings are wound to precise specifications.
 

Darco electric guitar strings meet the need for ultimate value. Sets are specially selected for rock and jazz. 
 

Made from a nickel/steel alloy for its  tonal qualities which are best suited to accent the strong resonating tendencies of most banjos.
 

Thomastik-Infeld
Solid steel core string with brilliance in tone and feel which is very durable