D'addario plain steel single strings. Available in a choice of gauges. D'addario Plain Steel Single String - Electric / Acoustic. Just a single string to replace broken one. Nothing more to say really.
D'Addario PL0095 Plain Steel Guitar Single String, 0095
5 Pack Single Guitar Strings High Quality Top 1st E Plain Steel Gauges 012
Ernie Ball Plain Steel 10 (.010") Single Guitar String
