STRING SET FOR VIOLA Prelude J910 XSM winding extra short scale, medium tension. Prelude strings are strings made from a solid steel core, unaffected by changes in temperature or humidity, and offer incredible bow response. Prelude strings give us the warmest sound available in solid steel core strings at the best price. Prelude is the teachers' preferred choice for their student's strings due to its unique blend of warm tone, economy, and durability. .