In the field of human computer interaction (HCI) the limitations of prototypes as the primary artefact used in research are being realised. Prototypes often remain open in their design, are partially-finished, and have a focus on a specific aspect of interaction. Previous authors have proposed `research products' as a specific category of artefact distinct from both research prototypes and commercial products. The characteristics of research products are their holistic completeness as a design artefact, their situatedness in a specific cultural context, and the fact that they are evaluated for what they are, not what they will become. This paper discusses the ways in which many instruments created within the context of New Interfaces for Musical Expression (NIME), including those that are used in performances, often fall into the category of prototype. We shall discuss why research products might be a useful framing for NIME research. Research products shall be weighed up against some of the main themes of NIME research: technological innovation; musical expression; instrumentality. We conclude this paper with a case study of Strummi, a digital musical instrument which we frame as research product.