parallel bars 
plural noun
A pair of parallel rails on posts used in gymnastics: a gymnast on parallel bars...
- Her routine on the parallel bars includes combinations that are unique.
- Women's gymnastic events include balance beam, uneven parallel bars, combined exercises, floor exercises, vaulting, and rhythmic sportive gymnastics.
- Check out the male and female weight lifters and body builders at Muscle Beach with it's free weights, rings, parallel bars, balance bar, and other gymnastics apparatus.