Case Slimline Trapper 31048 Yellow Synthetic Vintage 1940 -64 ~  

• Pattern Number: 31048. The "3" indicates a synthetic/composition handle, the "1" specifies a single blade, and "048" is Case's designated code for the Slimline Trapper frame. 
• Production Era: 1940 – 1964. The tang stamp during this block reads simply CASE XX (without dots or USA stamps). 
• Blade Configuration: One Blade — a long, slender Clip Point blade. 
  
• Blade Steel: Chrome Vanadium (CV) Carbon Steel. Note on material: During the 1940–1964 era, Case utilized their traditional high-carbon formula. If original, it will naturally darken and develop a gray or black patina over time, or show signs of pitting if not kept oiled. 
• Dimensions: Approximately 4-1/8 inches closed and roughly 7-1/4 inches overall when fully extended. 

• The "Delrin" Clarification: While modern collectors frequently refer to all vintage plastic-handled Case knives as "Yellow Delrin", DuPont did not commercially introduce Delrin (polyoxymethylene) until 1960. Case began transitioning to it in the early-to-mid 1960s. For a 31048 made between 1940 and 1960, the yellow handle is technically a composite/synthetic material (such as Tenite or polymer plastics) rather than true Delrin.
• Handle Appearance: A smooth, classic "banana yellow" finish featuring a Double Oval Open C "CASE" shield pinned into the front scale.
• Liners & Pins: Solid brass liners and brass pins holding the assembly together.
• Bolsters: Dual, polished nickel silver bolsters located on the pivot end (some variations from this era feature a barehead design where only the pivot end has a bolster.

• Never used, carried or sharpened
• No box
• Condition is near mint