A disc filter frame including a base member and a lever, said base member including, adjacent a first end thereof, a breathing aperture and a connection arrangement configured to connect to a respiratory device, said breathing aperture and connection arrangement being aligned so as to define an airflow channel therebetween; said lever being hingedly connected by a hinge mechanism at its proximal end to said base at said first end and including a sealing member shaped and configured to cover said breathing aperture, the lever being biased in a first position and selectively movable to a second position in which said sealing member seals said breathing aperture, the distal end of said lever being located and spaced apart from adjacent a second, opposing end of said base and configured to be manually pressed to move said sealing member from said first position to said second position.