This is the 7-inch model (86 05 180). Knipex also makes 6-, 10-, and 12-inch versions.
Opening the handles all the way causes the lower jaw to slide about 1/4 inch farther away from the upper.
The jaws are adjusted by pressing a spring-loaded button and sliding the pivot point up or down.
The lower jaw moves in response to a cam-like piece on the end of the upper handle.
The lower jaw slides in a channel and remains parallel to the upper in all positions.
The 7-inch model opens up to 1 3/8 inches wide. The 10- and 12-inch models open to 1 3/4 and 2 3/8 inches respectively.