Hi Frankief,
Some bars are compatible but usually only one way. The Airush bar cannot be used on the Ozone Edge due to both front line flagging system requiring pulleys in bridle to depower properly, and the Edge bar couldn't be used on the Varial due to depower length required (unless your middle name is DANGER)

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Don't use the Varial Bar on the Ozone, but quite OK to use the Ozone on the Varial except you wont have the depower length. Be cautious in gusty frontal winds!
I hope this makes sense.
DM
EDIT: Changing bars can work so long as the safety system is compatible. If you have a kite with a long single front line that splits into two front lines further up, then you most likely have a delta style kite with pulleys on the bridle. These kites can be used with either single or double front line (Y type or Virtual 5th) flagging safety systems.
A Fixed bridle of direct connected kite such as Rebel, Fuel, C4, Torch, Catalyst, Edge or any other
pulleyless bridle kite cannot be be used with a double front line flag kite unless you have a 5th line safety setup.
Sorry for the confusion earlier. A little birdie told me ......

DM