Check out all the models including the NEW model 2R! Standard Cardellini clamps have 5/8" shafts and pins or microphone threads. They're rust proof, with quick spin knobs and patented jaws that grip a variety of shapes.
A smaller, much lighter version of the Cardellini Clamp, with a 3/8" pin. Great for table top work, camera lock-offs, mounting laser pointers, or supporting the end of a long flag.