There are 3 long square pegs that connect the two sofa sections. The parallel sides of these bars are both drilled with holes, HOWEVER only one side is actually threaded. Luckily for me the first bar I attempted to screw together was on the unthreaded side and I had to separate the sections and correctly reposition all my bars. I would have been VERY upset had I attached the first or second bar and then found the next one inserted wrong. I would have had to undo all those connections. Since the screws don't even reach the other side of the bar, I don't know why they drilled both sides only to cause confusion. Seems the manufacturer wisened up and now the washers, bolts and wrenches are properly packaged. The only written instructions besides the pictures says connect the sections then attach the legs. I feel it's better to attach the legs first so you have some leverage when trying to pull the sections together. One hole in one of my bars didn't line up so I couldn't insert the screw. Also the center leg moved out of position a bit after I moved the sofa into position. But it was easy enough to correct.