The invention relates to pressure transfer device, system comprising the pressure transfer device, a fleet comprising the system and use of a pressure transfer device for pumping fluid at pressures above 500 bars, the pressure transfer device (1′, 1″) comprising a pressure chamber housing (1′, 1″) and at least one connection port (3′, 3″), the at least one connection port (3′, 3″) being connectable to a dual acting pressure boosting liquid partition device (2) via fluid communication means (26′, 27′; 26″, 27″), the pressure chamber housing comprises: - a pressure cavity (4′, 4″) inside the pressure chamber housing, and at least a first port (5′, 5″) for inlet and/or outlet of fluid to the pressure cavity (4′, 4″), - a bellows (6′, 6″) defining an inner volume (7′, 7″) inside the pressure cavity (4′, 4″), and wherein the inner volume (7′, 7″) is in fluid communication with the connection port (3′, 3″), wherein the pressure cavity (4′, 4″) has a center axis (C′, C″) with an axial length (L) defined by the distance between the connection port (3′, 3″) and the first port (5′, 5″) and a varying cross sectional area over at least a part of the axial length (L), and wherein the bellows (6′, 6″) is configured to move in a direction substantially parallel with the center axis (C′, C″) over a part of the axial length (L) of the pressure cavity (4′, 4″).