This knife is a must-have for roofers. You can put a straight blade in one slot, and a hook blade in the other slot; plus, you have a "pouch" to put extras of each type of blade so that you're never short of needed blades, and neither is the guy you're working beside (as you can provide for him, too!).Very easy to use. It's extremely helpful for roofers, and you're constantly switching between hook and straight blades.