The T0540 is a gloss optimizer, which means that it gives your images a glossy finish when it's being printed. While printing, your ink becomes placed onto the paper, and then it is coated by the gloss found within the T0540 cartridge. It gives your images that extra touch of professionalism, and is definitely a great effect on your pictures. It comes in 20ml cartridges, and can be delivered directly to you. Additionally, the gloss optimizer, although a new addition to the ink market, is quite affordable. Because it is a relatively new product, the T0540 is compatible with two printers: the Epson Stylus R800 and the Epson Stylus R1800.