I can't attest to the quality of the linked set as I don't own that particular brand and Sears came out with those when they switched their automotive specialty tools to being from Taiwan.
As others have said the flat metal piece is for releasing window crank retaining springs. The other two trim tools are great for removing door panels, splash shields, and most anything else held on by a removable plastic retainer. The curved one is handy for some stubborn door panels as the curve provides more leverage.
Another option would be to check out the Gearwrench trim tool offerings from Cripe distributing. They were selling the individual tools. It's handy to have a long and short trim tool.
