Eurotherm Chessell can provide you with top quality pens, cartridges and Charts for their Strip, Circular and video graphic recorders. For each unit the paper and pens are designed to work not only with each other, but also with the writing system of the recorder itself. Using Chessell consumables on a Chessell recorder will give optimum results, using pens and paper that weren't designed to be used together, or on your recorder can lead to: Ink bleeds, Smudged Charts, Faint trends, Trace too heavy, Short cartridge/pen life, No trace laid down or paper ripped on fast moving transients. Even if it has a Chessell part number, if it's not from us or one of our sales representatives, then it's not a genuine Chessell consumable.