Spyderco developed the Spyderco UK Penknife Folding Knife after the United Kingdom prohibited the carry of knives with locking blades. They began refining the classic slip-joint pocket mechanism with a notched joint and added two Spyderco features that define the modern folding knife: a pocket clip for convenient carry and their Trademark Round Hole for easy, ambidextrous one-hand opening. The blade is flat ground and features opposing jimping on the thumb ramp and index-finger choil for positive control.