The 24-kt, gold-plated New Harmony solid (or hollow weave) carbon fiber endpin comes only in the 10mm size.
The endpin can easily slide into fittings originally designed for hollow metal rods; take care not to over-tighten the screw, however, as this can damage the carbon fiber. If properly cared for, this endpin can be used for many years in standard cello endpin fittings.
This is the 24-kt, gold plated 10mmendpin, which comes in either the standard 20" length, or extended 24" length. Gold-plating is only available in 10mm fittings. Comes with a plastic lined rubber cap that you see here.
This item does not include fitting.