A spreader for lifting an intermodal transport container (22, 22a-d), the spreader comprising a main frame comprising a first travelling beam guide (26; 226) and, adjacent to said first travelling beam guide (26; 226), a second travelling beam guide (28; 228); a first travelling beam (30; 230) having a proximal end guided in said first travelling beam guide (26; 226) so as to allow movement along a first guide axis, and a distal end connected to a first twist-lock arrangement; and a second travelling beam (32; 232) having a proximal end guided in said second travelling beam guide (28; 228) so as to allow movement along a second guide axis, said first and second guide axes (A1, A2) being parallel, and a distal end connected to a second twist-lock arrangement, wherein the distal ends (38, 40) of said travelling beams (30, 32) are configured to variably extend from the respective travelling beam guides (26; 226, 28; 228) in opposite directions, so as to allow changing the axial distance (D L) between said first and second twist-lock arrangements (42, 44) to accommodate for containers (22, 22a-d) of different axial lengths, the spreader being characterized in that the main frame comprises a main beam formed of a first, upper C-beam (60; 260) of a relatively thicker material thickness (MT U1), said upper C-beam (60; 260) being oriented so as to define a downwards-facing channel; and a second, lower C-beam (62; 262) of a relatively thinner material thickness (MT L1), wherein said relatively thicker material thickness (MT U1) is thicker than said relatively thinner material thickness (MT L1), said lower C-beam (62; 262) being oriented so as to define an upwards-facing channel, said upper and lower C-beams (60; 260, 62; 262) facing each other to define an inner space comprising said upper and lower channels. a main frame comprising a first travelling beam guide (26; 226) and, adjacent to said first travelling beam guide (26; 226), a second travelling beam guide (28; 228); a first travelling beam (30; 230) having a proximal end guided in said first travelling beam guide (26; 226) so as to allow movement along a first guide axis, and a distal end connected to a first twist-lock arrangement; and a second travelling beam (32; 232) having a proximal end guided in said second travelling beam guide (28; 228) so as to allow movement along a second guide axis, said first and second guide axes (A1, A2) being parallel, and a distal end connected to a second twist-lock arrangement, wherein the distal ends (38, 40) of said travelling beams (30, 32) are configured to variably extend from the respective travelling beam guides (26; 226, 28; 228) in opposite directions, so as to allow changing the axial distance (D L) between said first and second twist-lock arrangements (42, 44) to accommodate for containers (22, 22a-d) of different axial lengths, the spreader being characterized in that the main frame comprises a main beam formed of a first, upper C-beam (60; 260) of a relatively thicker material thickness (MT U1), said upper C-beam (60; 260) being oriented so as to define a downwards-facing channel; and a second, lower C-beam (62; 262) of a relatively thinner material thickness (MT L1), wherein said relatively thicker material thickness (MT U1) is thicker than said relatively thinner material thickness (MT L1), said lower C-beam (62; 262) being oriented so as to define an upwards-facing channel, said upper and lower C-beams (60; 260, 62; 262) facing each other to define an inner space comprising said upper and lower channels.