Published at Friday, July 13th 2018, 14:35:43 PM by Beverley King. Shower Curtain. Another factor that determines who will buy what kind of shower curtain is the size and shape of it. The size of the tub area across the board vary in size, from a small space, to a walk-in room-of-a-shower, there is a need for a variety of differently sized curtains to be available to shoppers. Also, the shape of a is important. Whether the bar on one's shower is high enough to make the shower curtain needed a square, or whether the shower is long enough for the curtain to be rectangular decides who will buy what type.