I have those as well. They’re very sturdy, strong clamps but I find the size far too long for most uses. I used them on my workbench build, along with some 2′ and 3′ clamps and found the 4.5′ ones really difficult to maneuver. They’re still great value and will likely come in handy for future builds.
These are the 3′ ones I bought a while back: http://www.rutlands.co.uk/hand-tools/clamps-&-vices/clamps—bar/DKWK1/bar-clamps-with-heavy-duty-jaws