The Large Right Clamp also has a jaw length of 2-3/4" but with a larger Base Angle and and longer screws than the Long Right Clamp.  End Screws adjust Clamping Tubes to provide uniform pressure over the length of the clamp.  Two 1 inch Base Angle Notches allow locations to apply glue to inside corner of the jointand adding corner stiffeners.  It can also be used for joining other materials up to 9/16" thick.
It is well suited for structures and particularly handy at reaching over the large cornace at the top front wall of some structures.  A pair of clamps can hold longer parts from both ends.  One of the photos shows a Large Right Clamp being used as part of a drill fixture.