Window perf is a calendered adhesive-backed vinyl that is perforated with a pattern of round, evenly spaced holes. Window perf is sometimes called “see-through vinyl,” or “one-way vision film,” because it partially blocks vision from the outside, but not from the inside.
In most cases, the actual size of the holes are uniform (usually about 1.5mm). It’s the distance between the holes that determines the print coverage vs. visibility. For example, 50/50 window perf film means that 50 percent of the material is printable area and 50 percent is perforation. Window perf comes in a number of different hole configurations; 50/50, 60/40 and 70/30 are the most common. The first number in this designation represents the amount of printable area and the second number represents the amount of open (see-through) area. Therefore, a 70/30 window perf has a larger printable area but, less see-through area, than a 50/50 window perf.