Center-Fold Sheeting also referred to as Slit-On-Edge Tubing or U-Film, is polyethylene tubing which has been folded in half, and can be slit on either left- or right-handed side, and wound up on a roll.
It is measured width (in inches) x length (in feet). For example 12" x 100' Center-Fold Sheeting will open up to a sheet that is 24" x 100' Sheeting.