When to use reverse auction

Listing down the pre-requisiteds of a successful reverse auction,
- Proposed Spend:when proposed spend is large enough to attract supplier communities interest. More the value, chances of getting more suppliers.
-Adequate competition:The product/commodity should have adequate suppliers in the same geography. Reverse auctions can be successfully executed between two suppliers, wherein the participating suppliers are dependent on same client for their survival.
-Clear Specification:The purchase specs should be clearly defined without any ambiguity which will allow to release the cushion price at the fag end of competition.
-Availability: The product should be available with out any market distortion.