Half rectified high twist unsplit lamb gut, 120cm length.
Note for first time users of gut strings: Fine tuners must be removed if using a modern tailpiece. A baroque tailpiece is recommended. All contact surfaces must be perfectly smooth; tailpiece holes, bridge slots, nut slots, and tuning peg holes. Sharp edges anywhere can cause a gut string to break. Pre-stretching strings is highly recommended. Bring them slowly up to about 1 1/2 steps flat and leave overnight. Then slowly bring up to tension in the morning being careful that the strings slide in the bridge slots and do not pull the bridge forward. If unsure, it is best to work with a luthier.