The Dubuque UC-76A Wedgegrip universal cabinet shelf clamp is specifically designed for clamping shelves and cabinet units, due to the 90-degree orientation of the jaw to enable it to operate on a right-angle joint.
The jaw-style clamp on one end grips the wood and locks in place as the screw on the other end is tightened, giving you targeted clamping force and eliminating the need to access both sides of your project to make adjustments.
Because this clamp attaches much closer to the joint of your work-piece, there is much less risk of bowing that is common with traditional bar clamps.