A nice small Sargent #106 block plane. These are known as unadjustable, simply because the adjustment is manual. They are often called Apron planes or finger planes because of their size and because of the finger button.
This is a Sargent #106 with a Stanley Blade. It’s got a small chip behind the mouth which shouldn’t affect performance at all.
I’ve sharpened it for you, so take it out of the box, and use it.