From D'Addario:

D’Addario Classic Nylon Student strings are designed specifically for beginner classical guitarists. The traditional combination of silver-plated copper wound over nylon and clear nylon trebles, brings a charmingly mellow balance, which strikes a chord with students. Classic Nylon sets are also available in smaller sizes to accommodate learner instruments. Normal Tension strings are our best-selling tension, preferred for their balance of rich tone, comfortable feel, and dynamic projection.