The trunnion joint is a type of inclination joint with an axle passing through one or more cylinders. In the example shown here, each pillar is topped with a cylinder. The inclination axle passes through one of these, then the limb of the microscope, and then through the other pillar cylinder. Tension is adjusted with a lever on this model, though in many cases, there is no lever and a spanner wrench is needed to adjust the tension.