Faithfull 3 Square Engineers File 8" Bi-material handle for comfort and grip High carbon steel blade Strong and durable Hang Handle for convenient storage Faithfull 3 Square Engineers File 8" The Faithfull Three Square Second Cut Engineers File (sometimes described as a triangular file) has three flat sides and is used to file in acute internal angles, clean cut square corners, enlarge and clean up angular holes and sharpen serrated jaws and saw teeth. Fitted with a comfortable grip, it is ideal for professional and frequent DIY use. Features Sometimes described as a triangular file, it has three flat sides and is used to file in acute internal angles. For professional and frequent DIY use. Fitted with a comfortable handle.