A seal (40a, 40b) for installation within an assembly including a housing having a generally annular bore which extends along a central longitudinal assembly axis, and a generally cylindrical element disposed coaxially in the bore and radially spaced-apart from the bore to define a gap between it and the bore, the assembly having a gland (42a, 42b) defined between the element and the bore, the gland having a first end wall and a second end wall spaced-apart axially from the first end wall, and the gland having a peripheral side wall extending axially between the first and the second end wall and radially circumferentially about the assembly axis, the peripheral side wall having fluid passageway opening into it for providing a source of fluid pressure, the seal comprising: a generally annular body formed of an elastomeric polymeric material, the body extending around a central seal axis and configured to be receivable within the gland coaxially with the assembly axis intermediate the bore and the element, the body having a radial first end face disposable opposite the gland first end wall, and a radial second end face spaced-apart axially from the first end face and disposable opposite the gland second end wall, and the body having an inner diameter face extending axially intermediate the first and the second end face and disposable opposite the element, and an outer diameter face spaced-apart radially from the inner diameter face and extending axially intermediate the first and second end face and being disposable opposite the bore, the inner diameter face having a first lip portion extending radially therefrom towards the element, and a second lip portion axially spaced-apart from the first lip portion and extending radially from the inner diameter face towards the element, the first and the second seal lip being energizable responsive to fluid pressure received from the fluid passageway to sealingly engage the sidewall of the gland, characterised by a generally annular first anti-extrusion spring member extending around the seal axis, the first anti-extrusion spring member being moulded into the body outer diameter face adjacent the body first end face, and by a generally annular second anti-extrusion spring member extending around the seal axis, the second anti-extrusion spring member being moulded into the body outer diameter face adjacent the second end face, in which, with the seal being under pressure in the assembly, the first and second anti-extrusion spring members seal the gap on opposite ends of the seal to prevent the seal body from being extruded into the gap. a generally annular body formed of an elastomeric polymeric material, the body extending around a central seal axis and configured to be receivable within the gland coaxially with the assembly axis intermediate the bore and the element, the body having a radial first end face disposable opposite the gland first end wall, and a radial second end face spaced-apart axially from the first end face and disposable opposite the gland second end wall, and the body having an inner diameter face extending axially intermediate the first and the second end face and disposable opposite the element, and an outer diameter face spaced-apart radially from the inner diameter face and extending axially intermediate the first and second end face and being disposable opposite the bore, the inner diameter face having a first lip portion extending radially therefrom towards the element, and a second lip portion axially spaced-apart from the first lip portion and extending radially from the inner diameter face towards the element, the first and the second seal lip being energizable responsive to fluid pressure received from the fluid passageway to sealingly engage the sidewall of the gland, characterised by a generally annular first anti-extrusion spring member extending around the seal axis, the first anti-extrusion spring member being moulded into the body outer diameter face adjacent the body first end face, and by a generally annular second anti-extrusion spring member extending around the seal axis, the second anti-extrusion spring member being moulded into the body outer diameter face adjacent the second end face, in which, with the seal being under pressure in the assembly, the first and second anti-extrusion spring members seal the gap on opposite ends of the seal to prevent the seal body from being extruded into the gap.