"Thermalast" thermal imaging paper is laboratory tested to maintain image quality up to 7 years in normal office conditions...up to 2 years longer than required by DOT regulation. "Thermalast" is coated on the front and the back for image sharpness and durability. Unlike the inexpensive receipt and fax paper "Thermalast" will not fade or darken when stored or exposed to long term office conditions. 4 rolls per pack.