In one example in accordance with the present disclosure, a printing fluid container for a printing system is described. The printing fluid container includes a container body for holding printing fluid, a collar connected to the container body, and a cap removably engaging the collar. The collar has a plurality of collar teeth extending peripherally around the collar. The cap has a plurality of cap teeth extending peripherally around the cap. The cap teeth are configured for interfitment with the collar teeth such that rotation of the cap about the longitudinal axis in a first rotational direction effects cam-actuated removal of the cap from the collar.