30ml Nano Premium Black Refill Ink Kit for HP 920 920XL Ink Cartrodge and HP OfficeJet 6000, 6500, 7000 printers World-class Nano-technology! Smell: Normal odor; PH: 6~8; Particles: N/A; Stability: No settling in 3 years (at normal storage); Temperature: -15C no frozen, 70C no gelling; Lightfastness: 5~6 BWS; Waterfastness: 3 (average); Gasfastness: 4 (good); Fast drying time, even on the glossy paper!