The 5/16″ bit is the common size for threading a 3/8″ 16 tpi hole.    It has a 1 3/4″ flute length and the total length is 3 1/16″. The standard wood bit is longer and tends to “wander” if it hits a tight wood grain.

You may also like to buy the Bottoming Tap which cuts threads to the flat bottom.   This is recommended for the hard exotic wood.

There may be some wood or especially acrylic and resins that it might be easier to use the threaded inserts because they do not hold threads well and to help eliminate tear out.

These drill bits are made in America