A rail system is provided having two profile rails, between which a lamellar configuration having multiple lamellar elements is provided. The lamellar element is implemented for a roller blind device, which can be guided in a rail system like a folding blind, having a lamellar body and having at least two guide elements, which are situated on diametrically opposing sides of the lamellar body and extend in the transverse direction of the lamellar element, for holding and/or guiding in at least one guide groove of the rail system, at least one first guide element having at least one extension differing in the transverse direction in relation to at least one second guide element.