Olympus URF-V (9.9Fr?), actually 11Fr

The diameter of URF-V from Olympus company is known to be 9.9Fr. However, you can easily recognize that 11Fr ureteral access sheath is not available while you use the URF-V for RIRS because there are many creases in the distal tip which interfere with smooth movement of the flexible ureteroscopy. You can see the situation in the following picture. Therefore, we should use the ureteral access sheath of 12 Fr or larger in diameter.