0.5206" Dia, 2" Long Vermont Gage Class X Plus Pin Gage, manufacturer part number 141152060.
Specifications: Diameter of Measurement: 0.5206 in; Gage Function: Go (Plus); Class: X; Tolerance: 0.00004 in; Surface Finish: 4 Micro Finish; Overall Length: 2.0000 in.
Material: Tool Steel. Unit of measure: Inch.