Abstract: The invention relates to an automatic liquid chromatography system (1) with at least one fluid handling unit(s) (2), which is (are) provided as exchangeable, modular component(s). The system (1) further comprises at least one extension carrier (3) with at least one, preferably frameless, component position (C, C?, D, D?, E) for receiving at least one fluid handling unit (2). The system also comprises a base plate (6) and/or a cover plate (4). The at least one extension carrier (3) has at least one mechanical connecting element (15) and the at least one mechanical connecting element (15) projects from one plane into an adjacent plane during intended use, wherein the planes are selected from: extension carrier (3), cover plate (4) and base plate (6).