These Dr. Slick Twisted Loop Clamps come in 4" and 5" configurations and the straight jaws are half smooth and half striated. They are a truly groundbreaking series of clamps. By offsetting one loop and installing a gap between the loops, Dr. Slick has created a more ergonomic clamp with better control, dexterity and crushing power. These clamps can easily handle all streamside tasks. FYI, your thumb goes in the standard loop.