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.
Sargent #106 Type 1
Sargent #106 Type 2
This is sometimes called a gull wing based on the screw
Sargent #106 Type 3 (Last type)
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.