Thomastik Infeld RP110 Power-Brights Heavy Bottom 10-52 Electric Guitar Strings Light top combined with heavy bottom strings force the instrument to sustain. The high-E, B, and G are plain strings made of a highly flexible steel with brass coating to prevent corrosion. The D, A, and low-E strings are wound strings with a hexagonal core for greater flexibility and a special Magnecore alloy winding for high output.