Although not cheap, these professional, German-made wrenches are industrial quality and really a terrific value. The spring-lock button-locked slides have 19 positions. The jaws move absolutely parallel to one another. When you squeeze, an integral pivot forces the jaws tight. The leverage is huge. We have many hundreds of satisfied customers using them.
The German maker recently introduced a 6" size for handiness and we consider the range of the 3 sizes to now be perfect. For the fully equipped shop, all three have great utility.