How do you push an invisible product? That was the challenge facing ComponentGuard Inc., a Valhalla, N.Y., business that sells extended warranties for consumer electronic items.

CEO Robert Minnick came up with a novel approach: he put his service contract and membership card in a colorful plastic package that hangs from retail racks like a stereo accessory. With the new packaging, sales jumped to $6.1 million in 1990, from $1.4 million in 1989. In fact, sales for the first quarter in which the new package was used nearly equaled the revenues for all of 1989.