8x30ml Premium Grade Nano Pigment refill Ink kit for Epson 54 T0540-T0549 Ink cartridges and Epson Stylus Photo R800 , R1800 Printers 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).