JW lightest softshell! The main fabric weighs just 58 gm/m², half as much as a sheet of paper, but retains all the classic softshell properties: kinetic stretch comfort, wind & water resistance & extreme breathability. The very fine loop structure of the reverse side of the fabric side provides excellent wear comfort & a basic level of insulation. Stripped down to the bare essentials, this softshell jacket stows neatly in its own chest pocket & will also fit in any side pocket. Ultra-lightweight & packable technical summer softshell specifically designed for trail running.