This loyalty business model then looks at the strength of the business relationship; it proposes that this strength is determined by the level of satisfaction with recent experience, overall perceptions of quality, customer commitment to the relationship, and bonds between the parties. Customers are said to have a "zone of tolerance" corresponding to a range of service quality between "barely adequate" and "exceptional". A single disappointing experience may not significantly reduce the strength of the business relationship if the customer's overall perception of quality remains high, if switching costs are high, if there are few satisfactory alternatives, if they are committed to the relationship, and if there are bonds keeping them in the relationship. The existence of these bonds acts as an exit barrier. There are several types of bonds, including: legal bonds (contracts), technological bonds (shared technology), economic bonds (dependence), knowledge bonds, social bonds, cultural or ethnic bonds, ideological bonds, psychological bonds, geographical bonds, time bonds, and planning bonds.