Press Button Knife Co #1000 INVINCIBLE antique switchblade knife w Etch

Vintage Press Button Knife Co INVINCIBLE model switchblade made in Walden, NY sometime between 1912 and 1923. The knife measures 4 7/8 inches closed and 8 9/16 inches open with steel liners and nickel silver bolsters & button. The clip blade blade is 96% full with most of the original finish under a light patina and some light scratches. The tang is stamped PRESS BUTTON KNIFE CO WALDEN, NY on the tang and the backside is blank which means it was likely made between 1912 and 1923. Amazingly the original acid INVINCIBLE blade etch can be clearly read! Hard to find these with any of the original etch intact because the etches were so fragile and easily worn off with use/cleaning. The jigged bone scales are in very good condition with no cracks.  The knife functions well with the blade tip below the liners closed, opens strong when button pressed and locks open with about 1/16" up and down at the tip. It does rattle if shaken with the blade open as most of these do. This is a nice working example of a 100+ year old American made switchblade with good etch! VG+ condition.