An advantage of buying by performance or function over other specification methods is that it provides: evidence that the buyer has given thought and careful study to the need and the ways in which it may be satisfied. the opportunity for the potential supplier to establish how to make the most suitable product. the potential for equitable competition by ensuring that the suppliers are quoting for exactly the same material or service. a standard for measuring and checking materials as supplied. an opportunity to purchase identical requirements from a number of different sources of supply. See Answer the opportunity for the potential supplier to establish how to make the most suitable product.