A metal seal (115; 215; 315) for a flat face fluid coupling, comprising: an annular seal body (141; 241; 341) defining a central axis and a central passage (144; 244; 344) extending axially through the seal body (141; 241; 341) along the central axis; and a plurality of seal retainers (145; 245; 345) circumferentially spaced apart along a radially inner portion (139; 239; 339) of the seal body; each of the plurality of seal retainers (145; 245; 345) having a fixed end (146; 246; 346) fixed to a radially inner portion (139; 239; 339) of the seal body, a free end (147; 247; 347) spaced from the seal body (141; 241; 341), and an intermediate portion (148; 248; 348) extending between the free end (147; 247; 347) and the fixed end (146; 246; 346), each of the plurality of seal retainers (145; 245; 345) being configured to engage a retainer wall of the fluid coupling with a retaining force for securing the seal (115; 215; 315) to the fluid coupling; wherein the annular seal body (141; 241; 341) has opposite axially facing first and second flat annular sealing surfaces (142, 143; 242, 243; 342, 343), and characterised in that the annular seal body (141; 241; 341) further has a radially outer annular angled portion (151; 251; 351) that is inclined relative to the first flat annular sealing surface (142; 242; 342), the annular angled portion (151; 251; 351) being configured to enhance stiffness around a circumference of the annular seal body (141; 241; 341), and the annular angled portion (151; 251; 351) being configured to engage a face of the fluid coupling to generate a moment of force about a portion of each of the plurality of seal retainers (145; 245; 345) for enhancing the retaining force of each of the plurality of seal retainers (145; 245; 345) acting against the retainer wall of the fluid coupling. an annular seal body (141; 241; 341) defining a central axis and a central passage (144; 244; 344) extending axially through the seal body (141; 241; 341) along the central axis; and a plurality of seal retainers (145; 245; 345) circumferentially spaced apart along a radially inner portion (139; 239; 339) of the seal body; each of the plurality of seal retainers (145; 245; 345) having a fixed end (146; 246; 346) fixed to a radially inner portion (139; 239; 339) of the seal body, a free end (147; 247; 347) spaced from the seal body (141; 241; 341), and an intermediate portion (148; 248; 348) extending between the free end (147; 247; 347) and the fixed end (146; 246; 346), each of the plurality of seal retainers (145; 245; 345) being configured to engage a retainer wall of the fluid coupling with a retaining force for securing the seal (115; 215; 315) to the fluid coupling; wherein the annular seal body (141; 241; 341) has opposite axially facing first and second flat annular sealing surfaces (142, 143; 242, 243; 342, 343), and characterised in that the annular seal body (141; 241; 341) further has a radially outer annular angled portion (151; 251; 351) that is inclined relative to the first flat annular sealing surface (142; 242; 342), the annular angled portion (151; 251; 351) being configured to enhance stiffness around a circumference of the annular seal body (141; 241; 341), and the annular angled portion (151; 251; 351) being configured to engage a face of the fluid coupling to generate a moment of force about a portion of each of the plurality of seal retainers (145; 245; 345) for enhancing the retaining force of each of the plurality of seal retainers (145; 245; 345) acting against the retainer wall of the fluid coupling.