Welded Hollow Metal Frame Profiles and Jamb Depths
Here are the more standard jamb profiles. This is the "conventional" hollow metal frame, meaning it is meant to be welded and is indeed welded most of the time it is used. However, it can also be used as a knockdown 3 piece unit and is installed that way at times.
The "throat" is the open space in the back of the frame between the backbends...the part that wraps the wall. The first dimension is the jamb depth...which is the overall frame size. Jamb depths are available from 3" to 20"...under 4 3/4" jamb depth will be a single rabbet frame. These are standard double rabbet profiles.
Note that all the frames have a 1/2" backbend, except for the 5 3/4" frame, which has 7/16" backbends. This is an industry wide standard as it creates a 4 7/8" throat in a 5 3/4 frame...which is what a standard stud wall is when finished...3 5/8" metal studs with one layer of 5/8" drywall each side. So the 5 3/4 frame will wrap the standard stud wall just right when all is done.