Recent studies show that many tolerance specifications in technical drawings—such as sizes or geometrical tolerances—are incomplete or ambiguous. This represents significant potential for cost reduction and efficiency improvement. ISO GPS is the international standards system for Geometrical Product Specifications (GPS) that enables the unambiguous definition of the function and geometric characteristics of components. ISO GPS has gained increasing importance in industry following the withdrawal of Part 2 of ISO 2768 and the introduction of ISO 22081. ISO GPS differs from the American standard ASME Y14.5.

This compact introductory book provides a practical entry into tolerancing and focuses on the key questions: What needs to be specified, and how should the specification be implemented? It is intended for apprentices and mechanical engineering students as well as professionals working in design, planning, quality assurance, and manufacturing.

The book covers the following topics:
- The tolerancing process
- Fundamentals of Geometrical Product Specifications (ISO GPS)
- Principles of dimensional and geometric tolerancing
- Datums and datum systems
- General tolerances
- Non-rigid parts in accordance with ISO 10579

The second edition incorporates all relevant standards for Geometrical Product Specifications, including ISO 8015, ISO 5459, ISO 14405, ISO 1101, and ISO 10579. It also addresses the updates introduced in ISO 5459, in which the default method for establishing datums on planar surfaces was revised.

In addition to explaining the relevant standards, the book presents a proven practical approach to assigning tolerances, illustrated through typical components such as a shaft, a sheet-metal part, and a plastic molded part. These examples can serve as templates for your own components.