Greenlee Conduit Pistons Use with blower or vacuum power fishing systems to pioneer the line through the conduit run Flexible foam body for an airtight seal Color-coded end disk with embossed size markings for fast; easy selection Strong steel center rod with loops on both ends Pistons available for all types and sizes of conduit 1/2 through 6"" Greenlee 2-1/2'' Conduit Piston 621