Murray, I've used this head for a couple of years, for 4x5 and smaller. My 4x5 is a Horseman FA metal field cam and a Calumet-copy Tachihara woodfield, and it works fine with both of them. I have 4x5 monorail, but no way I would put on this head, it goes on the bogen 3047. The lever on the left side tightens the QR plate down snug, it operates on a "half turn", hard to explain, but it does not get in the way of the camera. My only disappointment has been I recently purchased a Gitzo 3530s pod, which is a series 3, and the 2272m head (which is a series 2, smaller diameter base than the systematic plate) will not do 100% vertical without rotating the QR plate on the cam 90 degrees. However, this is not an issue with 4x5, and goes away when I put on the 1321 leveling base. I wish gitzo made a PT head for series 3, I've seen some on ebay, but they look like soemthing out of star wars. good luck, Tom Seattle