0.73 mm - Unsplit Lamb Gut - Sheep Gut
violin - 2-a
bass viol - 1-d
viola - 1-a
viola d`amore - 2-a`
treble viol - 2-a
pardessus - 3-a
The use of unsplit lamb gut, besides being closer to the historical reality of the string makers of the past, has also led to strings with unexpected superior acoustical and mechanical properties, as compared to those produced with gut strips. The HU type strings have a surface that has been smoothened only the minimum needed to guarantee that the string is not false; the string is then slightly oiled.
Standard length is 120 cm up to diameters of 1.90 mm.
You can read more about this type of strings here: