RPK 18cm Russian Prison Knife Vintage Automatic Black & silver coilspring

Vintage RPK 18cm Russian Prison Knife sliding button coil spring knife. It is believed these knives were made by inmates to be sold to the public to raise money for the prisons in the 1950s through 80s, I believe. I'm still researching it. These knives are all one-of-a-kind pieces of Russian cutlery Folk Art and they are a lot of fun to collect and make wonderful display pieces. They can be found in all shapes and sizes and so far I haven't found any two exactly alike. This knife measures 17.5cm (6 7/8 inches) open with steel liners, bolsters & button. The saber grind scimitar blade is full and shiny with light scratches. The scales (handles) are in nice condition and are black synthetic with steel bolsters. The knife works great with the blade tip seating deep closed, good snap and Tight lockup. Sliding button to open and close. Does not rattle if shaken when open. EX+ condition.