RPK 22cm Russian Prison Swing Guard rectangular button automatic knife

Vintage RPK 22cm Russian Prison Swing Guard rectangular button lockback automatic knife likely made in a prison in the USSR sometime before 1990. It is believed that inmates were allowed to make knives to be sold to generate revenue for the prisons at that time. The knife measures 22cm (8 5/8 inches) open and 4.75 inches closed with aluminum liners, bolsters & button with nickel silver safety and folding guards. The flat spear swedge blade is full with original finish and no maker's mark anywhere on the knife. The synthetic brown scales are in very good condition. The knife works well with blade tip deep & centered closed, strong snap and tight lockup open. No rattle if shaken with blade open. Button is VERY hard to push on this one so don't buy it unless you have a STRONG thumb. No danger of this one ever opening inside a pocket.  ;^) EX condition.