Check the listing for details. Thomastik-Infeld PI64C Peter Infeld Orchestra Double Bass C Extension String -. Condition: New. Listed at 151.25 USD. Masterful Midrange with a Centered Core and Expansive Palette Experience a new level of playability with Thomastik-Infeld Peter Infeld double bass strings. Building on Thomastik-Infeld's renowned spiral core design, Peter Infeld strings boast a groundbreaking blend of materials, enabling them to achieve a bold growl and rich sustain for jazz bass players; meanwhile, orchestra bassists enjoy improved bowing paired with commanding projection. Engineered for consistent performance, these strings deliver a remarkably robust midrange with a centered tonal core that bursts forth with clarity and nuance. Sweetwater bassists find that they put an expansive sonic palette at your command, giving you exacting, expressive control over your tone.