3x30ml Nano Premium Black Refill Ink Kit for HP 901, HP 901 XL Black Ink Cartridges for HP printer OfficeJet J4524, OfficeJet J4540, OfficeJet J4550, OfficeJet J4580, OfficeJet J4624, OfficeJet J4660, OfficeJet J4680, OfficeJet J4680c ... 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); Shelf Life: 3 Years