I don't know if they all do, but mine came with a rubber strip that fits over the top edge of the flares so that all the gaps are filled when you screw it back to the bodywork. Measure the centre of the wheel arch and mark the body work, I used a long spirit level and lined it up on the centre of the wheel so that they were all in the same place, line it up with centre of the flare and stick it on with masking tape. Have a good look to see that it's level and then draw around the top edge with a soft pencil. Take the tape off, lower the flare down about an inch and draw around it again to give you a line to make your cut on. They do pull back into the shape of the body work when you start to tighten them up.
Good luck
Gav