A device for forming a fistula between blood vessels includes a tubular body having a central lumen, a flange attached to the tubular body and projecting outwardly from an outer body surface, and one or more vanes projecting inwardly into the lumen so as to induce helical flow in blood passed through the lumen between first and second vessels joined via the fistula. For this purpose, at least one clamping jaw, in the area of its radially inside surface, has at least one projection which extends in the circumferential direction toward the other clamping jaw and which projects into the gap. The OMS automates the outage measurement process and is more accurate, efficient and cost effective than previous outage measurement systems. The slider has an ejecting-directional end as an end thereof in the ejecting direction. The phase shifter gives the phase shift so that the two input lights to the optical multiplexer have a phase difference of 60 degrees, and the first and second Mach-Zehnder modulators are driven by three-level signals. The abrasive is composed of a base material as an elastic body and abrasive grains, wherein the abrasive grains of 10 to 90% by weight are compounded and dispersed into the base material of 90 to 10% by weight such that a content rate of the abrasive grains in the abrasive is 10 to 90% by weight when an amount of the abrasive is 100% by weight.