An assembly suitable for dispensing liquid from a compressible bag, the assembly comprising an apparatus and a flexible mat, the apparatus comprises a housing having a dispensing end and an opposite rear end, a floor comprising a flat floor surface, a pair of parallel guiding tracks, a roller arrangement comprising a roller body having a first and a second roller body ends and a roller surface with a cross-sectional circumference, the roller arrangement has a first roller arrangement end and a second roller arrangement end, respectively engaged with said respective guiding tracks, wherein said guiding tracks are located to guide said roller arrangement to roll said roller arrangement from the rear end location towards the dispensing end, and a drive arrangement engaged with said roller arrangement for driving said roll of the roller arrangement from the rear end towards the dispensing end, said drive arrangement comprises a spring arrangement, wherein said spring arrangement comprises at least one helical torsion spring located within the roller body, said mat has a length extending between a first mat end and a second mat end, wherein the first mat end is mounted to or adapted to be mounted to said roller body and the mat is located at least partly on the flat floor between said guiding tracks when said roller is located at said rear end location, preferably said second mat end is located closer to said dispensing end than the first mat end, at least when said roller arrangement is located at said rear end location, wherein said mat preferably is flexible and suitable for being rolled onto the roller body, and wherein said spring arrangement comprises a loading station for loading said spring arrangement, and wherein said roller arrangement comprises a snap lock for temporarily holding said roller body in said loading station. the apparatus comprises a housing having a dispensing end and an opposite rear end, a floor comprising a flat floor surface, a pair of parallel guiding tracks, a roller arrangement comprising a roller body having a first and a second roller body ends and a roller surface with a cross-sectional circumference, the roller arrangement has a first roller arrangement end and a second roller arrangement end, respectively engaged with said respective guiding tracks, wherein said guiding tracks are located to guide said roller arrangement to roll said roller arrangement from the rear end location towards the dispensing end, and a drive arrangement engaged with said roller arrangement for driving said roll of the roller arrangement from the rear end towards the dispensing end, said drive arrangement comprises a spring arrangement, wherein said spring arrangement comprises at least one helical torsion spring located within the roller body, said mat has a length extending between a first mat end and a second mat end, wherein the first mat end is mounted to or adapted to be mounted to said roller body and the mat is located at least partly on the flat floor between said guiding tracks when said roller is located at said rear end location, preferably said second mat end is located closer to said dispensing end than the first mat end, at least when said roller arrangement is located at said rear end location, wherein said mat preferably is flexible and suitable for being rolled onto the roller body, and wherein said spring arrangement comprises a loading station for loading said spring arrangement, and wherein said roller arrangement comprises a snap lock for temporarily holding said roller body in said loading station.