The basses of the Professional 550 series in Medium Tension feature finely calibrated carbon trebles from the 558CMHT Trebles Set. Carbon Trebles in Medium High Tension (for a scale length of 65 cm): The higher specific density of the material allows for a significantly thinner string compared to nylon trebles. This results in a brighter, more brilliant tone that responds more quickly. Compared to nylon trebles, the sound is richer in overtones and more harmonious. The smaller diameter allows for better string vibration with less partial tone detuning. The bass set in Medium Tension from the 550MT set includes 2x D4, A5, and E6. Calibrated strings made from the finest materials produce a homogeneous, powerful tone with great projection. The Professional series enables solo artists to fully explore the sound possibilities of their instrument. An extra D4 string is included in the bass set. The silver-plated winding wire of the bass strings (nylon silk core) features a special surface treatment that prevents tarnishing and discoloration over time. The strings are spun under tension, allowing them to quickly hold their tuning after being installed.