It's good to keep your customers informed.
James is a storekeeper who has Bill, a customer asking him if he knows anything about a particular battery he sells.
James wants to answer Bill's question.
James tells Bill that the battery is quite long lasting and that it's one of the more complimented ones by his repeat customers.
James tells Bill that although he sells the battery he knows nothing about it apart from what's on the box.
Bills is happy to learn some extra information to help him figure out if he wants to make the purchase.
Bill is annoyed that he can't get the information he's seeking and is miffed at James for not knowing his products.