The aim of the project is to study open book accounting (OBA) in the sale of capital equipment. OBA was established as a new field in the financial management literature in the 1990s. The research stems from the observation that firms have become increasingly interdependent. On average, companies purchase more than 50% of their goods and services from business partners. At the same time, the products purchased have become increasingly complex and require close cooperation and information exchange between firms. The OBA literature focuses on such systematic, confidential financial and non-financial information exchanges. A large number of studies have been conducted with a focus on component purchases where it has been shown that OBA is designed and used in different ways depending on whether the components are standardized or specified by the supplier, the customer or both. At the same time, OBA has not been studied for capital equipment, which have been important products for the Swedish export industry and are characterized by large investments and even larger consequential costs. Capital equipment requires continuous maintenance with spare parts and downtime can lead to high consequential costs. OBA could be used here, but its design is complicated by the self-interest of customers, subcontractors and independent service companies. This leads to three questions: 1) How can OBA be used and 2) designed in the sale of capital equipment? 3) How does this form of OBA differ from previously studied ones?