Stockholm 2015: high backrests surround these upholstered seats by Swedish furniture brand Lammhults (+ slideshow).

Lammhults' designers Johannes Foersom and Peter Hiort-Lorenzen named their flexible sofa system Portus, the Latin word for a port, harbour or safe place.

The range comprises a bench, a support cushion, and a back. The bench forms the base element and comes in three sizes.

A high or low back can be mounted on any of the benches and a low cushion added for extra support. These combinations result in a bench, an armchair or a sofa.

Portus is designed for flexible use in shared public and private spaces. "The thought is that the elements constituting Portus can be put together in different ways in order to make the pieces of furniture useful in many various areas," the designers told Dezeen.

"Portus with the lower back can be both a nice and comfortable easy chair, with a stool to rest your tired feet upon, or a sofa for the afternoon rest," they continued.

"With the high back Portus is an intimate 'room within a room' for rest or conversation, a mobile conference room, a place for concentration and work."

The frame comes in wood or steel, the seat and back are made from upholstered moulded-polyurethane foam, and legs are available in steel tubing, natural or stained solid ash.

"The frame is plain and uncomplicated, almost archetypical, and refers to Nordic simplicity and restraint when it comes to use of material," said a statement from Lammhults.

Foersom and Hiort-Lorenzen introduced Portus at Stockholm Furniture Fair earlier this month as an update of their 1988 Newport sofa for the brand.