For the success of a technical product, it must be perceived by the user as suitable as possible for its use. In the early phase of product development, prototypes are used to validate the perceived suitability for use. They differ in their prototype fidelity through appearance and haptics and they influence the users' perception of suitability for use. Due to lack of knowledge, no generalizable effect of the prototype fidelity is available yet. In the presented research project, a reduction approach is investigated with the aim to build up an understanding for the influences on the subjective suitability for use, and thus to enable an objective assessment. This work demonstrates the approach through a study design conducted with Power-Tools and test subjects.