Any knife that uses a split-back spring construction falls into the whittler category. The split-back design uses two springs that support a large single blade on one end, and two smaller blades on the other. The larger blade uses both spings, and each small blade rides on its own spring. There is more work that goes into the construction of this type of knife than almost any other style of knife made. The whittler has probably been responsible for more wood shavings than any other knife. A Whittler '08 is three-bladed pen knife with a Clip master blade on one end and two small cutting blades of equal length (usually a Short Clip and Pen) on the other end. The Half Whittler '08WH is a two bladed version of the Whittler '08 pattern with Clip master blade on one end and a pen blade on the opposite end. Case started making these sometime prior to 1940.