A downhole tool for projecting a projectable element downhole in order for the tool to perform an operation in a well, comprising: - a tool body having a tool outer diameter (OD T) and a longitudinal extension, - a radial bore extending in a radial direction (L R) perpendicularly to the longitudinal extension, the radial bore having a first bore part having a first inner diameter (ID 1) and a second bore part having a second inner diameter (ID 2) being larger than the first inner diameter, - a projectable element arranged and forming a piston in the radial bore, the projectable element having an open first end and a closed second end, the projectable element having a retracted position and a projected position where the second end is projected from the first bore part, the projectable element comprising at the second end a first element part having a first outer diameter (OD 1) corresponding to the first inner diameter (ID 1) and a second element part having a second outer diameter (OD 2) corresponding to the second inner diameter, and in the retracted position the projectable element and the second bore part define an annular cavity closed by the second element part, - a hollow base part having an open end and a closed end, the open end extending into the open first end of the projectable element, forming a chamber therebetween, the open end of the hollow base part having an outer diameter (OD H) which corresponds to an inner diameter (ID P) of the projectable element, - at least one spring element arranged in the chamber and connected to the closed first end of the projectable element and to the closed end of the hollow base part for retraction of the projectable element, and - a pump configured to pump fluid into the chamber via a fluid channel to move the projectable element into the projected position, wherein the annular cavity is filled with fluid which leaves the annular cavity as the projectable element changes to the projected position, minimising the annular cavity. - a tool body having a tool outer diameter (OD T) and a longitudinal extension, - a radial bore extending in a radial direction (L R) perpendicularly to the longitudinal extension, the radial bore having a first bore part having a first inner diameter (ID 1) and a second bore part having a second inner diameter (ID 2) being larger than the first inner diameter, - a projectable element arranged and forming a piston in the radial bore, the projectable element having an open first end and a closed second end, the projectable element having a retracted position and a projected position where the second end is projected from the first bore part, the projectable element comprising at the second end a first element part having a first outer diameter (OD 1) corresponding to the first inner diameter (ID 1) and a second element part having a second outer diameter (OD 2) corresponding to the second inner diameter, and in the retracted position the projectable element and the second bore part define an annular cavity closed by the second element part, - a hollow base part having an open end and a closed end, the open end extending into the open first end of the projectable element, forming a chamber therebetween, the open end of the hollow base part having an outer diameter (OD H) which corresponds to an inner diameter (ID P) of the projectable element, - at least one spring element arranged in the chamber and connected to the closed first end of the projectable element and to the closed end of the hollow base part for retraction of the projectable element, and - a pump configured to pump fluid into the chamber via a fluid channel to move the projectable element into the projected position,