The use of common anthropometric tables often is not of any help when designing them for disabled people. This article addresses the advantage of first doing an observational study on the use of similar aids by disabled people. From that study, the relevant variables and critical areas can be learned. When users participate in the design process, the newly developed item probably will be innovative in comparison to just a desk research and development project. This means that a large sample is not necessary to find the potential for improvement. The study also delivers a better understanding of the fit of a particular product. This article discusses tools in anthropometry can help the designer understand the relation between dimensions and decide what should be adjustable and what should be fixed or produced in different sizes.