Press Button Knife Co INVINCIBLE antique Pick bone switchblade knife

Vintage Press Button Knife Co INVINCIBLE model switchblade made in Walden, NY sometime between 1900 and 1923. The knife measures 4 7/8 inches closed and 8 11/16 inches open with steel liners and nickel silver bolsters & button. The clip blade is marked PRESS BUTTON KNIFE CO WALDEN, NY on the tang and the backside is stamped US PAT 470605. The blade is about 96% full and has been lightly cleaned with some pitting and light scratches. The dyed picked bone scales are lighter color than most and in very good condition with a couple of stable hairline cracks in the back scale. The knife functions well with the blade tip below liners closed, opens strong when button pressed and surprisingly tight lockup when open with about 1/16" movement each way at the tip. Does rattle if shaken when open as most of these 100+ year old switchblades do. This is a nice working example of a 100+ year old American made switchblade in VG+ condition.