Collimators, testing telescopes and autocollimators are indispensable instruments for the optical workshop. The application range covers angle measurement, directional adjustment, qualitative evaluation of optical systems, radius measurement and others. Collimators, testing telescopes and autocollimators of MOELLER-WEDEL are world-wide known for their excellent quality, rather unlimited lifetime and their modular design. All basic components of collimators, testing telescopes and autocollimators are of modular design, the components are freely interchangeable and, of course, precisely matched to each other. Free interchangeability allows manifold combination possibilities and ensures economic solution of problems.