Press Button Knife Co #1000 INVINCIBLE antique switchblade nice blade

Antique Press Button Knife Co INVINCIBLE model switchblade made in Walden, NY sometime between 1892 and 1923. The knife measures 4 7/8 inches closed and 8.5 inches open with steel liners and nickel silver bolsters & button. The blade is marked PRESS BUTTON KNIFE CO WALDEN, NY on the tang and the backside is blank. The blade is 92% full or better with heavy patina, light scratches, light pitting and spotting, but overall good blade. The picked bone scales are in very good condition with no cracks.  The knife functions well with the blade tip just below the liners closed, opens strong when button pressed and locks open with about 1/4" up and down and some side to side movement at the tip. Rattles if shaken when open. This is a nice working example of a 100+ year old American made switchblade. VG+ condition.