AAI has improved their previous Non-Cabled Single Bar Trainer to this new and improved fully-adjustable version:

Non-Cabled Adjustable Single Bar TrainerWith the lowest setting at 12″ high, this versatile bar can now be used as the ultimate handstand bar in the gym for practicing pirouetting skills.  Raise it by any 6″ increment all the way up to 72″ high, and practice any of your other low bar skills.

This bar is well-designed and is sure to become one of the most useful single bar trainers found in the gym.

AAI Non-Cabled Adjustable Single Bar Trainer Flyer from American Gymnast