When I coat seams on drywall I use a box (also called a “flat box”) equipped with an adjustable handle which I extend when coating seams on ceilings. At its shortest the handle is 42 inches long and it extends to 62 inches. I have a short handle that I have been using when I am only taping walls with horizontal seams; it is 32 inches long. The typical handle has a brake. The brake is engaged by pressing the lever at the far end of the handle. The brake holds the box in a desired position so the box is easy to position over a wall or ceiling seam and it is also engaged as the box is lifted off the drywall surface and is held on until the box is repositioned over the next seam. The brake is released when actually applying the compound to the seam. The whole setup takes some getting used to, but the process is efficient and yields good results.
The box is filled with joint compound and once positioned over a seam physical pressure is applied through the handle. The handle is attached to a hinged cover on the back of the box. Pressure against this cover forces compound out of the mouth of the box. As the box is pulled along a seam the compound that is forced out is smoothed out with a blade along the tail edge of the mouth. As with most boxes physical pressure is required to force the joint compound out of the box mouth in a consistent flow and to smooth the compound out at the same time. Typically more than one pass is required to achieve a smooth seam with feathered out edges. So when coating seams on walls you can see how it is a little awkward and physically difficult to work with a tool that has a long handle. Of course when coating seams on ceilings or vertical seams on walls the long handle with a brake is necessary.
The Wizard handle from AMES is a shorter handle that the company claims offers better control over the box when coating horizontal seams. I have to say that I agree. When coating horizontal seams with the Wizard handle I was able to maintain consistent pressure throughout the joint, and I was able to maneuver the box more easily near corners. In addition, I really liked being able to coat all the seams in closets with the box instead of by hand as I have been doing. It is very fast and easy to attach to a box so when changing to a longer handle for coating ceiling seams the transition is very simple. There’s also likely to be less of a learning curve compared to a box equipped with the long handle and brake.