If by lime scale filter they mean a mesh screen to prevent the scale flakes from getting in your cup, then I agree that would be nice, the screen on mine lets s

If by lime scale filter they mean a mesh screen to prevent the scale flakes from getting in your cup, then I agree that would be nice, the screen on mine lets small flakes through. If by filter they want to prevent limescale in the first place, that requires an ion exchange resin and I highly doubt any kettle includes that or anyone would want a kettle that includes that. Or it would require an even less practical membrane that the water would be pumped through at high pressure. Or a two stage kettle where the that distills the water for you. If the kettle claims to have a filter to prevent scale, i.e. remove calcium, then the kettle is lying.