This is a double bass endpin socket. I'm offering it with a genuine 10mm diameter, 40cm long endpin. The retail price of this product is approximately 33,000 yen. I have actually used it, and it responds very well. Tip Φ29.5mm Base Φ32.5mm Insertion part 54mm Total length 98mm There is no manufacturer's name listed, so I can't be certain, but it appears to be a standard ULSA Rosewood. If the diameter of your double bass is smaller than this, you can have a luthier expand it for you, so I hope this is helpful.