mediumwhat am-i

The man who makes it doesn't use it; the man who buys it doesn't need it; the man who uses it doesn't know it. What is it?
Common Wrong Answers
“A bed”
A bed is made for personal use, and the person who buys it does need it for sleep, which contradicts the riddle.
“A car”
A car is both used by the owner and purchased for personal need, which doesn't fit the criteria of the riddle.
“Clothes”
Clothes are worn by the person who buys them, and they are needed for covering and comfort, making this answer incompatible with the riddle's clues.