Product modularity offers added benefits for the companies with respect to reduce lead-time, improve assemble ability, promote product family and enhances customers' satisfactions. Such modularity offers an opportunity to mix and match all the components of a product into a standardized modular product. The focus of this research is to introduce the concept of modularity within selected Omani companies (mainly small and medium size enterprises, SMEs) and eventually to measure the modularity level within their products portfolios. To measure such modularity level necessary design data from a selected Omani SME's products portfolios is collected and analyzed by design structure matrix (DSM) tool. The modularity level is measured through clustering the collected data related to components interdependences. This research is also concentrated to provide a methodological framework to develop modules that acts as a guideline to improve modularity level of the selected Omani SMEs existing products and/or new product portfolios.