A roller blind mounting system including at least one roller, at least one telescopic end plug and at least two brackets. The telescopic end plug is engageable within an end-opening of one of said rollers. The end plug includes a hollow body and a telescopically movable member or plunger co-axially positionable with respect to the hollow body such that a first axial extending length portion of the plunger projects from the hollow body and a second axial extending length portion is held within the hollow body. The plunger is telescopically movable between a first end position in which the first portion of the plunger projects from the cylindrical body and a second end position in which at least part of the first portion is inserted into the cylindrical body.