All About Pocket Knives

I picked up this Case Tested XX at an auction today and remember seeing it on e-bay. 3 1/4" Bone handle. Two blades. Brass bolsters. I Don't see a number on the blade tang. It went pretty high if I remember right. Im pretty sure the master blade is supposed to be notched out, but for what purpose? Electricians? This is the second one Ive seen so far. I can't find the value in my Knife Price Guides. Maybe someone also has an idea for value and a better resource book. I currently have the Knife Collectors Guide and American Premium Guide to Knives and Razors. Thanks for the help.

If the closed length is 3-1/4", then it is a 30 pattern, so it would be a 06230-1/2. A similar knife 3-5/8" closed would be an 06245-1/2. I am not sure that I have ever seen the smaller 30 pattern with a clip master blade. The blade is chipped out, not made that way.