From A319 CFM CDL 57-01 Wing Tip Fence
One may be missing provided exposed interior structure is covered, protective material is inspected before each flight and replaced if necessary.
Performance:
Take off and approach climb limiting weights are reduced by 10080kg (22223lbs)
En route performance limiting weight is reduced by 756kg (1667lbs)
Fuel consumption is increased by 1.69%
Caveat emptor!
mcdhu