Stanley Heavy-duty corner clamp: has an articulating design that allows for work pieces of equal or varying thickness to be joined at right angles. Its reversible-head design allows it to be used as a parallel clamp, and comfort and maximum torque can be achieved with the bi-material tri-lobular handle. Mounting holes allow the clamp to be securely attached to work surfaces. It has a heavy-duty cast zinc construction for durability, weighs 1.01 kg, has a throat depth of 30 mm and a clamping capacity of 57 mm.
How to use (similar product):
https://www.youtube.com/watch?v=-prOM-qhhU0