A printing fluid cartridge configured to be mounted to a cartridge mounting portion comprising an optical sensor (114, 116) and at least one contact, the printing fluid cartridge comprising: at least one electrical interface (75, 76, 77) configured to allow an electrical access to an integrated circuit provided to the printing fluid cartridge and configured to be electrically connected to the at least one contact; and a light attenuating portion configured to be inserted between a light emitter and a light receiver of the optical sensor and to be detected by the optical sensor, the light attenuating portion is a rib; wherein the printing fluid cartridge is configured to be inserted into the cartridge mounting portion in an insertion direction in an upright position, and the printing fluid cartridge in the upright position has a width in a width direction, a height in a height direction, and a depth in a depth direction, wherein the width direction, the height direction, and the depth direction are perpendicular to each other, and wherein the at least one electrical interface (75, 76, 77) comprises a first electrical interface, a second electrical interface, and a third electrical interface aligned and spaced apart from each other in the width direction, wherein the second electrical interface is positioned between the first electrical interface and the third electrical interface, characterized in that the depth direction is parallel with the insertion direction; and the at least one electrical interface (75, 76, 77) and the light attenuating portion are positioned, such that the second electrical interface and the light attenuating portion intersect a plane which is parallel with the height direction and the depth direction. at least one electrical interface (75, 76, 77) configured to allow an electrical access to an integrated circuit provided to the printing fluid cartridge and configured to be electrically connected to the at least one contact; and a light attenuating portion configured to be inserted between a light emitter and a light receiver of the optical sensor and to be detected by the optical sensor, the light attenuating portion is a rib; wherein the printing fluid cartridge is configured to be inserted into the cartridge mounting portion in an insertion direction in an upright position, and the printing fluid cartridge in the upright position has a width in a width direction, a height in a height direction, and a depth in a depth direction, wherein the width direction, the height direction, and the depth direction are perpendicular to each other, and wherein the at least one electrical interface (75, 76, 77) comprises a first electrical interface, a second electrical interface, and a third electrical interface aligned and spaced apart from each other in the width direction, wherein the second electrical interface is positioned between the first electrical interface and the third electrical interface, the depth direction is parallel with the insertion direction; and the at least one electrical interface (75, 76, 77) and the light attenuating portion are positioned, such that the second electrical interface and the light attenuating portion intersect a plane which is parallel with the height direction and the depth direction.