This is must-have Black Diamond piton on your nailing rack. It excels in small cracks too small for an angle but too big for a Pecker or Tomahawk. Lost Arrows are extremely durable. Usually you can avoid nailing with a clean aid placement. But sometimes, you need these.
These are becoming less essential on walls for good reason: there is better and better clean climbing gear. Before you reach for one of these pitons, first try a Moses Cam Hook, DMM Brass Offsets or a micro cam. But if none of these fit, the Lost Arrow is there for you. It is still a staple of any nailing rack and has been since John Salathé first came up with the design. Having a little piece of history on the rack is not bad!