A cross-flame duct for connecting adjacent combustors (1, 2) in a gas turbine engine, the cross-flame duct comprising: a first duct extending along a longitudinal axis and configured to be coupled to a first combustor, the first duct comprising; a first outer sleeve having a first end configured to be coupled to the first combustor and a second end on an opposite end from the first end, and a first inner housing positioned within the first outer sleeve and having a first end adjacent the first combustor and a second end extending from the second end of the first outer sleeve; a first cooling chamber positioned between an outer surface of the first inner housing and an inner surface of the first outer sleeve; and a second duct extending along the longitudinal axis and configured to be coupled to a second combustor, wherein the second duct is configured to slidably receive the first duct, the second duct comprising; a second outer sleeve having a first end configured to be coupled to the second combustor and extending toward the first duct to slidably receive the second end of the first inner housing within a second end of the second outer sleeve, a second inner housing positioned within the second outer sleeve and having a first end adjacent the second combustor and a second end extending toward the second end of the second outer sleeve, and a second cooling chamber positioned between an outer surface of the second inner housing and an inner surface of the second outer sleeve, characterised in that the second end of the first inner housing and the second end of the second inner housing do not overlap with each other. a first duct extending along a longitudinal axis and configured to be coupled to a first combustor, the first duct comprising; a first outer sleeve having a first end configured to be coupled to the first combustor and a second end on an opposite end from the first end, and a first inner housing positioned within the first outer sleeve and having a first end adjacent the first combustor and a second end extending from the second end of the first outer sleeve; a first cooling chamber positioned between an outer surface of the first inner housing and an inner surface of the first outer sleeve; and a first outer sleeve having a first end configured to be coupled to the first combustor and a second end on an opposite end from the first end, and a first inner housing positioned within the first outer sleeve and having a first end adjacent the first combustor and a second end extending from the second end of the first outer sleeve; a first cooling chamber positioned between an outer surface of the first inner housing and an inner surface of the first outer sleeve; and a second duct extending along the longitudinal axis and configured to be coupled to a second combustor, wherein the second duct is configured to slidably receive the first duct, the second duct comprising; a second outer sleeve having a first end configured to be coupled to the second combustor and extending toward the first duct to slidably receive the second end of the first inner housing within a second end of the second outer sleeve, a second inner housing positioned within the second outer sleeve and having a first end adjacent the second combustor and a second end extending toward the second end of the second outer sleeve, and a second cooling chamber positioned between an outer surface of the second inner housing and an inner surface of the second outer sleeve, a second outer sleeve having a first end configured to be coupled to the second combustor and extending toward the first duct to slidably receive the second end of the first inner housing within a second end of the second outer sleeve, a second inner housing positioned within the second outer sleeve and having a first end adjacent the second combustor and a second end extending toward the second end of the second outer sleeve, and a second cooling chamber positioned between an outer surface of the second inner housing and an inner surface of the second outer sleeve, characterised in that the second end of the first inner housing and the second end of the second inner housing do not overlap with each other.