Irwin Tools’s Folding Utility Knife Series includes BladeLock Technology, which prevents blades from pulling out of the handle and the ability to change blades only when a release button is engaged. A built-in wire stripper, cast finger grooves and trigger-grip handle are included in the FK100. The FK150 has built-in blade storage that holds up to two blades as well as finger grooves and trigger-grip handle. The FK250 integrated a foldout screwdriver for 1-in. insert bits in addition to the features of the other models.