Needs.
Customers want problems solved. Tell them you know that. If you convince a customer you understand his needs he will believe you can satisfy them.

Collateral.
Collateral materials (fliers, web pages, advertising, etc.) describe products. But good collateral shouldn't be a laundry list of specifications. Catalogs of features don't sell things. Instead, you must focus on a prospective customer's needs. Once that's done, you can explain how his specific requirements are met by your product.

Accessible.
A qualified prospect whose needs are accurately identified is almost a customer. Clearly stated, well-produced, technically complete descriptions then become valuable and appreciated. They are the last measure of convincing that a prospect wants. They help provide credibility and comfort.