The twist of a ball spline is given as angular movement per linear foot of spline and varies by size. Below are the approximate worst case twist values by size:
Ball Circle DiameterTwist per ft 3/81 degree, 15 minutes (1.25 degrees) 5/840 minutes (.67 degrees) 130 minutes (.5 degrees) 1.520 minutes (.33 degrees) 215 minutes (.25 degrees) 2.510 minutes (1.7 degrees) 310 minutes (1.7 degrees)
Thomson ball splines are typically used for power transmission application like paper converting rather than precision indexing applications and as such we don't publish the above twist values in the catalog.  If your application requires tight indexing tolerances please contact application engineering for assistance.