The Identi-Pen is ideal for use on all thermal materials (e.g. NC, ZX, TX, PX, SX), which typically do not keep ink as well with typical markers and pens. If you use thermal material and wish to write on it without the ink running, this pen was designed with your needs in mind! In addition to these applications, these pens work very well with our vinyl signage, injection-molded stakes, and t-stakes. Available individually in black only or in packages of 4 colors (blue, red, black, and green), these pens are a reliable and efficient manage inventory or display products in colorful and creative ways.