The Vintage Gibson Mona Steel No 240 Strings are plain-wound strings designed for acoustic guitars. Made in the United States, these strings are specifically tailored for 4-string acoustic guitars. As a custom bundle, this set of Gibson strings offers a unique and vintage appeal for musicians seeking high-quality materials and craftsmanship. Mona Steel is the material used in these strings, ensuring durability and a distinctive sound for acoustic guitar players looking to enhance their musical experience with a touch of nostalgia and authenticity.