I definitely likes like a manual hose crimper. I use a hydraulic version all the time at work. The dies should be labeled in even numbers. They are is 1/16 of an inch increments. So a 1/4" = 4 and 1/2 = 8. I don't know how high of pressure that thing is good for but I wouldn't use it on a brake hose but it might be good for an a/c hose. You have to crimp it down until both die halves touch. That would be a good tool to have but you may never use but it's nice to have just in emergencies.