Ernie Ball Hybrid Slinky Classic Rock n Roll Pure Nickel Wrap Electric Guitar Strings - 9-46 Gauge. Classic Rock N Roll strings consist of pure nickel steel wrapped around a tin plated high carbon steel core for a warm rich tone that compliments many playing styles including jazz rock and blues. Each set is packaged in an ultra low humidity environment with Ernie Ball s element shield packaging to ensure every set is as fresh as the day it was made.