The one that I installed myself was only 6", and I used ratchet straps to pull them together (using the proper casket grease). With 2 ratchet straps, it was easy. I added an elbow on the pond side a year later to raise the water level and needed to make a wooden jig so the ratchet straps would pull it on evenly. I have 15" and 12" on my other 2 ponds and they used machines to push them together.