Wound guitar strings are made up of a central core wire and an outer wrap which travels around the core. This central steel core wire comes in two main shapes: hexagonal shaped and round shaped (or more commonly referred to as hex core and round core). 

Back in the 50’s and 60’s, wound strings were exclusively constructed using round cores, however, in recent times, hex core strings have been more widely used by many string manufacturers and continues to be the most popular core type used today.

There are still a handful of brands producing round core strings and Fender are the latest brand to add round core sets to their lineup in the form of their Classic Core range. Typically, round core strings deliver a softer feel and tend to have more flexibility than a hex core string but also produce a warmer and boomier tone.

For a more in-depth look at the differences between these two core shapes, be sure to check out our blog post .

Here’s what Fender say about their Classic Core sets:

"Fender Classic Core electric strings go straight to the heart of classic tone for modern guitar. Designed with “vintage-spec” round core wire rather than the modern hexagonal type, Classic Core strings sound and feel perfectly seasoned as soon as you put them on your guitar. They deliver more expansive lows, softer highs and extra flexibility for expressive bends."