An OTF Knife, also known as an out-the-front knife, sliding knife, telescoping knife, or angel blade, is a pocketknife with a blade that opens and closes through a hole in one end of the handle. Contrast this with the majority of knives, which are either standard folding knives or are "fixed blade" sheath knives (having no mechanical operation). "OTF" only refers to the basic portion of the knife's mechanical operation where the blade slides parallel with the handle to deploy. Switchblades and gravity knives provide a great variety of different OTF mechanisms.