Oasis GPX+ Classical Guitar High Tension GPX Carbon Trebles/Medium Tension Sostenuto Basses High-endurance properties for longer life Long-lasting tone and sustain Lighter tension than comparable nylon strings The brilliance of these fluorocarbon (carbon treble) strings does not rely on the typical stiff hard action of other carbon trebles The same concert-quality sound is here, with far less effort, in Oasis GPX+ strings