3x30ml Nano Premium Water-Resistant Black Pigment Ink for HP 21 Black Ink Cartridges for HP Printer DeskJet 3910, DeskJet 3915, DeskJet 3918, DeskJet 3920, DeskJet 3930, DeskJet 3930v, DeskJet 3938, DeskJet 3940, DeskJet 3940v, DeskJet d1330, DeskJet d1360, DeskJet d2330, DeskJet d2360, DeskJet d2430, DeskJet d2445, DeskJet d2460, DeskJet f340, DeskJet f380, DeskJet f4180mfp, OfficeJet 4310, psc 1400, psc 1401, psc 1402, psc 1403, psc 1406, psc 1408, psc 1410, psc 1410v, psc 1410xi, psc 1415, psc 1417 ... Particles: &lt;0.5 micron (Average&lt;100 nanometer); Stability: No settling in 2 years (at normal storage); Temperature: -12C no frozen and 50C no gelling; Lightfastness: 7-8 BWS; Rubfastness: 5 (Excellent); Waterfastness: 5 (Excellent); Gasfastness: 5 (Excellent).