The search works by keywords. You can also use the following mechanisms to refine your search: - Quotation marks ( " ): Quotation marks are used to search for a set of consecutive keywords. For example "35 gallons" will return all results where there is " 35 gallons" consecutively in one of the search fields, but will not return, for example "35 per gallons". - Minus ( - ): the minus sign ( - ) allows you to exclude keywords. For example , valve -polypropylene will return all results that match valve, but not those that contain polypropylene.