Abstract: A self-aligning roller bearing having inner and outer bearing ring elements and at least one row of roller elements disposed in between. The inner bearing ring element having a retaining flange provided on a first axial side of the roller bearing being configured for preventing the roller elements from falling out from the roller bearing. The roller bearing having a first sealing ring element located at the first axial side for sealing the first axial opening, the first sealing ring being rotatable in relation to the inner bearing ring and seals against a sealing mating surface of the inner bearing ring. The retaining flange has at least one filling slot configured for allowing the roller elements to be inserted in-between the inner and the outer bearing ring elements during assembly of the roller bearing, and the sealing mating surface being axially outside the at least one filling slot.