'Merge or join two tables SQL Server

I have a table with two columns Item, Qty and another table with Product, Quantity.

Table A

Item Qty
a 10
a 15
a 5
b 10

Table b

Product Quantity
a 10
a 20
b 5
b 5

The output that I'm looking for is this:

item Qty Product Quantity
a 10 a 10
a 15 a 20
a 5 NULL NULL
b 10 b 5
NULL NULL b 5


Sources

This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.

Source: Stack Overflow

Solution Source