Thorlabs has released Polaris, an ultrastable kinematic mirror mount for 25.4-mm-diameter optics. Fabricated from heat-treated stainless steel that minimizes temperature-dependent hysteresis, it incorporates a matched 100-tracks-per-in. actuator and bushing pairs that minimize drift and backlash, and it has ball contacts with sapphire seats at all contact points. It provides the stability necessary for use in alignment-sensitive applications and is designed for long-term use in multiple setups. A flat-spring mechanism secures the optic in place, regardless of the ambient temperature, eliminating the need to glue the optic into position. The optics can be easily swapped in and out of the mount, which is equipped with an M4 counterbore for post mounting.