A disc brake system comprises a mounting hub and at least one disc supported by the mounting hub. An optical image of the sample A is projected on an image-pickup element via the optical system, and is converted into a picture signal by means of the image-pickup element. The source follower circuit 10 comprises a source follower stage 12 and a bias stage 14. The semiconductor film for film quality evaluation is exposed through an opening formed through interlayer insulating films, so that it is possible to immediately start evaluation of the film equality. The wearable mount having a coupler configured to couples to a mount coupling of a mobile device and a fastener that fastens the wearable mount to a location, the location, a set of functionalities of the mobile device being based on the location.