The phrase most commonly refers to a specific series of collectibles or literary works, depending on whether you are looking for a physical "piece" or a piece of media: The Fantasy Knife Collection

: These pieces are often crafted with stainless steel blades, manual opening mechanisms, and accents of silver or 24-karat gold. Literary & Media Works

: Consists of 12 distinct folding knives, each representing a month of the year (e.g., the "January" or "April" piece).