A bleed air assembly for a gas turbine engine, the bleed air assembly comprising a transfer tube assembly (218,318) comprising: a fluid transfer tube (250,350) configured to extend through a casing (224,234) and to provide compressed air from a compressor to a component external to the compressor, wherein the fluid transfer tube has a tube portion configured to extend through the casing (224;324); and a seal assembly (230,330) for the fluid transfer tube (250,350), the seal assembly (230,330) comprising: a base member (236,336) having a first side configured to mate with the casing (224,324) and a second side opposite the first side; a housing (232,332) configured to mate with the second side of the base member (236,336) and to surround a portion of the fluid transfer tube (250,350); and a bellows (260,360) configured to surround the fluid transfer tube (250,350) and be positioned between the housing (232,332) and the casing (224,324), wherein the fluid transfer tube (250,350) defines a longitudinal axis and the bellows (260,360) is positioned about the fluid transfer tube (250,350) and extends from a first end (262,362) to a second end (264,364) spaced a distance along the longitudinal axis from the first end (262,362), characterised in that: the seal assembly (230,330) further comprises a wear ring (270,370) disposed between the housing (232,332) and the bellows (260,360), the wear ring (270, 370) extending circumferentially about the fluid transfer tube (250, 350) and comprising a composite material that is secured to an outer surface (255, 355) of the fluid transfer tube (250, 350); the first end (262,362) is configured to float with respect to the fluid transfer tube (250,350) and the second end (264,364) is fixed with respect to the fluid transfer tube (250,350); and the bellows (260,360) and the wear ring (270,370) are configured to enable movement (266, 267, 366, 367) of the tube portion (250,350) with respect to the casing (224,324). a fluid transfer tube (250,350) configured to extend through a casing (224,234) and to provide compressed air from a compressor to a component external to the compressor, wherein the fluid transfer tube has a tube portion configured to extend through the casing (224;324); and a seal assembly (230,330) for the fluid transfer tube (250,350), the seal assembly (230,330) comprising: a base member (236,336) having a first side configured to mate with the casing (224,324) and a second side opposite the first side; a housing (232,332) configured to mate with the second side of the base member (236,336) and to surround a portion of the fluid transfer tube (250,350); and a bellows (260,360) configured to surround the fluid transfer tube (250,350) and be positioned between the housing (232,332) and the casing (224,324), wherein the fluid transfer tube (250,350) defines a longitudinal axis and the bellows (260,360) is positioned about the fluid transfer tube (250,350) and extends from a first end (262,362) to a second end (264,364) spaced a distance along the longitudinal axis from the first end (262,362), characterised in that: the seal assembly (230,330) further comprises a wear ring (270,370) disposed between the housing (232,332) and the bellows (260,360), the wear ring (270, 370) extending circumferentially about the fluid transfer tube (250, 350) and comprising a composite material that is secured to an outer surface (255, 355) of the fluid transfer tube (250, 350); the first end (262,362) is configured to float with respect to the fluid transfer tube (250,350) and the second end (264,364) is fixed with respect to the fluid transfer tube (250,350); and the bellows (260,360) and the wear ring (270,370) are configured to enable movement (266, 267, 366, 367) of the tube portion (250,350) with respect to the casing (224,324). a base member (236,336) having a first side configured to mate with the casing (224,324) and a second side opposite the first side; a housing (232,332) configured to mate with the second side of the base member (236,336) and to surround a portion of the fluid transfer tube (250,350); and a bellows (260,360) configured to surround the fluid transfer tube (250,350) and be positioned between the housing (232,332) and the casing (224,324), wherein the fluid transfer tube (250,350) defines a longitudinal axis and the bellows (260,360) is positioned about the fluid transfer tube (250,350) and extends from a first end (262,362) to a second end (264,364) spaced a distance along the longitudinal axis from the first end (262,362), the seal assembly (230,330) further comprises a wear ring (270,370) disposed between the housing (232,332) and the bellows (260,360), the wear ring (270, 370) extending circumferentially about the fluid transfer tube (250, 350) and comprising a composite material that is secured to an outer surface (255, 355) of the fluid transfer tube (250, 350); the first end (262,362) is configured to float with respect to the fluid transfer tube (250,350) and the second end (264,364) is fixed with respect to the fluid transfer tube (250,350); and the bellows (260,360) and the wear ring (270,370) are configured to enable movement (266, 267, 366, 367) of the tube portion (250,350) with respect to the casing (224,324).