We brought one of the square ones for work with the double burner. Certainly works well. The only thing that is not great is the insulation which is like a fibre matting( that can be harmful if breathed in ) then you have to rub a clay stuff on before using but we have now brought proper fire bricks to replace the matting with.
You would be much better getting a square one other than the round one, the round one is a bugger to put the paste onto, and as someone has mentioned with the square one it is easier to use firebricks, its also a bigger forge and more stable.
These are very good cheap forges, and they work very well even with one burner, obviously gettting the metal at , and holding it at a critical temperature is not easy, but a very useful tool. Easier to seal the nd of a square one too, with a firebrick.
I built my own , two tar burners and a big bottle of propane , and then to turbo charge it I removed the nozzles from another tar burner and put pure oxygen through that for those times when hot isn't hot enough .