Cellotex is the trade name and is four by eight feet or avalible in ceiling tiles. Single sided is what I use and the 4x8 sheet cut down to my 'L' shaped work surface. The unfinished brown side takes pins very well for that type of building. The white finish side also makes an excellent cutting surface. I do replace usually every few years depending on what type of building I am doing the most of at the time.
John