ND Brand 4 X 30ML premium ink refill kit for Lexmark #43 #44 Black & Color ink cartridges and printer X4850, X4875, X4950, X4975, X6570, X6575, X7550, X7675, X9350, X9575, Z1520 ... ND Brand 4x30ml premium water-based UV resistant dye ink; Smell: Normal odor; PH: 6-8; Particles: N/A. Stability: No settling in 3 years (at normal storage) Temperature: -15C no frozen and 70C no gelling Lightfastness: 5-6 BWS; Waterfastness: 3 (Average); Gasfastness: 4 (Good).