An annular seal assembly for use in a fluid mover with a cylinder having an annular groove therein for receiving said seal assembly, the annular groove having a first radial wall and a second radial wall, the fluid mover having a reciprocating rod, which reciprocates in the cylinder through the seal assembly, the seal assembly comprising: a tangentially-cut ring assembly receivable in the annular groove, the tangentially-cut ring assembly having an outer peripheral face and an inner peripheral face, the inner peripheral face for sealingly engaging the reciprocating rod and defining an inner diameter, D, the tangentially-cut ring assembly having a first annular face forming a first seal surface and a second annular face arranged to sealingly engage the first radial wall of the annular groove, the first annular face and the second annular face defining a thickness, h, therebetween, the tangentially-cut ring assembly comprising a plurality of arcuate segments; and a radially-cut ring assembly receivable in the annular groove, the radially-cut ring assembly having an outer peripheral face and an inner peripheral face, the inner peripheral face for engaging the reciprocating rod, the radially-cut ring assembly having an annular face sealingly engaged with the first seal surface of the tangentially-cut ring assembly, the radially-cut ring assembly comprising a plurality of arcuate segments; wherein the tangentially-cut ring assembly has a plurality of passages extending from the outer peripheral face of the tangentially-cut ring assembly to within at least 1.0 mm of the inner peripheral face of the tangentially-cut ring assembly, each passage of the plurality of passages having a respective diameter, d i, for each passage of the plurality of passages, characterized in that d i < 2.6 mm; each passage of the plurality of passages at the inner peripheral face of the tangentially-cut ring assembly is at least a distance of 1.5 mm from the second annular face at the inner peripheral face of the tangentially-cut ring assembly and no greater than a distance of 0.75 × h from the second annular face at the inner peripheral face of the tangentially-cut ring assembly; the plurality of passages in the tangentially-cut ring assembly number at least πD 3 h + d, where d is the mean value of the diameters (d i) of the plurality of passages; and each passage of the plurality of passages extends through a distance no closer than 0.1 mm to the inner peripheral face of the tangentially-cut ring assembly. a tangentially-cut ring assembly receivable in the annular groove, the tangentially-cut ring assembly having an outer peripheral face and an inner peripheral face, the inner peripheral face for sealingly engaging the reciprocating rod and defining an inner diameter, D, the tangentially-cut ring assembly having a first annular face forming a first seal surface and a second annular face arranged to sealingly engage the first radial wall of the annular groove, the first annular face and the second annular face defining a thickness, h, therebetween, the tangentially-cut ring assembly comprising a plurality of arcuate segments; and a radially-cut ring assembly receivable in the annular groove, the radially-cut ring assembly having an outer peripheral face and an inner peripheral face, the inner peripheral face for engaging the reciprocating rod, the radially-cut ring assembly having an annular face sealingly engaged with the first seal surface of the tangentially-cut ring assembly, the radially-cut ring assembly comprising a plurality of arcuate segments; wherein the tangentially-cut ring assembly has a plurality of passages extending from the outer peripheral face of the tangentially-cut ring assembly to within at least 1.0 mm of the inner peripheral face of the tangentially-cut ring assembly, each passage of the plurality of passages having a respective diameter, d i, for each passage of the plurality of passages, characterized in that d i < 2.6 mm; each passage of the plurality of passages at the inner peripheral face of the tangentially-cut ring assembly is at least a distance of 1.5 mm from the second annular face at the inner peripheral face of the tangentially-cut ring assembly and no greater than a distance of 0.75 × h from the second annular face at the inner peripheral face of the tangentially-cut ring assembly; the plurality of passages in the tangentially-cut ring assembly number at least πD 3 h + d, where d is the mean value of the diameters (d i) of the plurality of passages; and each passage of the plurality of passages extends through a distance no closer than 0.1 mm to the inner peripheral face of the tangentially-cut ring assembly.