An improved structure of a mouse pen is disclosed. The filter has a housing made up of a peripheral wall, which extends around the entire periphery of the filter, and opposing filter-retaining screens. The mask assembly includes a frame and a plurality of unit masks. The coupling covers a portion of both the tubular body and tip body and is made from a first material and a second material, where the first material is different from the second material. These features are then stored as patterns for later recognition of live input signal streams.