Clear Monofilm 5mil
A light weight performance material for boardsails and telltale windows. This see-through mylar film does not have any threads running through it: this makes the tear strength not as high as the X-Ply Monofilm, but it does have great stretch resistance.
Installation is made easier if Seamstick double-sided tape is used to adhere the window material to the fabric before sewing and cutting. After the material is sewn in place, use scissors to trim away the fabric and expose the window.
Many windsurfer sails are made from Monofilm.