A passive filter may include at least one elliptical filter unit and at least one asymmetric rejection filter unit coupled in series with the elliptical filter unit. A probe tip including one or more light sources and a plurality of light receivers is provided. Thus, in an example embodiment, a single user can control the presentation of information to the audience via gestures. A fixture plate may be used in combination with the underfill to add additional strength and simplify handling. The abrading tools include clamping mechanisms to quickly and reliably secure sanding paper, bristled sheets, polishing cloths, and the like, to the tool, while at the same time providing the operator with increased agility and ability to reach relatively hard to reach or oddly shaped surfaces. The jig is also equipped with an inspection-object supporting portion, provided with a member for supporting the small parts at the predetermined portion on the base.