It’s one of the most common reasons for a “no deal” on the ABC show “Shark Tank”: a one-off product doesn’t attract repeat customers.

So, why — and how — do some companies manage to sell items that never have to be replaced?

Marketplace Weekend guest host David Lazarus looks into two indestructible industries. First, Zane Schenk explains his role from the New West KnifeWorks production floor in Idaho Falls, Idaho. Schenk says he has been making knives for as long as he can remember — perfect, since they guaranteed to last forever, too.

Second, with longevity in the kitchen comes cast-iron skillets. Bob Kellerman, CEO of Lodge Cast Iron, says his company makes some of the most popular skillets on the market. These are passed down from generation to generation in many families, usually getting better with age.