Pirastro Obligato Upright Bass StringsPirastro's Obligato strings are made with a modern synthetic multi filament fiber core. This allows Obligato strings to produce a warm and full sound that also have a brilliant and rich overtone spectrum with focused tone. The have excellent response throughout the entire dynamic range of the instrument with great tone volume. Their core also gives the strings fantastic resistance to changes in temperature and humidity as well as tuning stability. A