Great roof mount for OTA antenna. I thought be easier to mount the base to the roof first. Otherwise it would be hard for one person to mark, drill holes, screw base to the roof with the J-pole still attached. But then its a bit tricky to get the J-pole bolts adj bolts in place due to having to insert them from the inside of the J-pole. Aa better design might be to weld the nuts on the inside of the tube so one could easily insert the bolts from the outside.
Well made accessory for mounting the good size antenna I was using it for. We had a severe thunderstorm roll through here a while back with very violent winds and this thing held up pretty good. I did have to go up and re-tighten a couple of nuts but that's it.....