A folding duty knife that might be used in rescues, cutting open boxes of gear, slicing the banding on ammunition crates, or as a weapon in extreme circumstances requires a high-quality knife manufactured by a company known for excellence in designing various types of knives. The most important feature of a good knife is the design and material of the blade. The design of a blade--its shape, serrations, and length--depends on the preferences of the user and how it is to be used. The steel quality of a blade is measurable, and blades of good-quality steel are durable and easily sharpened. With a folding knife, consideration should be given to the ease with which it can be opened and closed and the reliability of the locking mechanism when the blade is open and in use. Regarding locking mechanisms, the lock-back knives have a long history, but the user generally must use both hands to open or close the blade. Liner-lock and frame-lock knives have similar locking mechanisms and can be easily opened and closed with one hand. Another feature to consider when purchasing a knife is the grip construction. The materials typically used in good-quality folding knives are durable and lightweight; however, some composite grip materials used in folding knives, such as Zytel, are vulnerable to degradation from constant exposure to solvents, including gasoline. The most important feature of a grip is that it enables users to maintain a grip under harsh and slippery conditions. A table shows manufacturers and features of specific knives, including price.