A sheet gripping assembly for thin pliable sheet material, such as plastic film comprising either a single sheet or two separate sheets disposed face to face. The sheet gripping assembly has an elongate base with a longitudinal channel opening through one longitudinal side of the base for receiving the sheet material to be gripped and a sheet lock insert which coacts with the channel side walls to grip the sheet material between interengaging longitudinal edge formations on the sidewalls and insert. A second sheet lock insert is provided to secure one sheet of dual sheet material within a second channel in the base.