PRESS BUTTON KNIFE CO Invincible Hunter Bone antique switchblade knife

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 1/4 inches open with steel liners and nickel silver bolsters and button. The blade is about 88% full and shiny with some scratches and is marked PRESS BUTTON KNIFE CO WALDEN, NY on the tang and the backside is blank. 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 fully when button pressed with thumbnail and locks open well with just a hint of movment each way at the tip. Does not rattle if shaken when open. This is a nice working example of a 100+ year old American made switchblade. VG condition.