（７）Two-ply toilet paper

I found a word "Ply" on the toilet tissue's packaging. It said 250 X 2-Ply sheets per roll. I have seen many "plies" in specifications of FRP (Fiber-Reinforced Plastic) at work. I have thought it is a technical term or something but my guess seemed to be wrong. The number of plies (stacked sheets) is commonly used to express the quality of toilet paper. I bought two rolls of toilet paper at the supermarket in Saudi Arabia. Its packaging also said that two rolls = 61 m. This means the length of the sheet is 122mm. ( 61000/ 50 0=122) But I did not know why they use the number of sheets to describe the length of a toilet roll.  By the way, the toilet tissue was Kleenex brand.

ply: fold, thickness, or strand fo which something is made