These blades come in several different amounts, but they all are the same universal size and will fit inside any brand name razor blade knife. They are approximately three inches in length and have two notches in the top center to hold the blade in place. Stanley has probably the nicest set up, because usually you have to undo a Phillips head screw in the center of the case to get to the blade and replace it. But Stanley, has a set up where there is a button located on top at the front, that will allow you to replace the blade without having to open it up.
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