BERNHARDT manufactures its 2SL bags with side gussets from a single roll of film. These bags have only one lengthwise seal down the middle of the front. When used with a liner, they may be UN certified. They come in laminated or co-extruded films, with EVOH or aluminium barrier film.
The films with 4 or more layers include a polyamide layer. This gives the bags extra strength for vacuum packing.
BERNHARDT can guide you in the choice of material and type of barrier film most suited to your packaging needs.