Certain mattresses

SERTAS

Think of a brand that might help you sleep soundly with its name starting like "serene."

The clue "Certain mattresses" hints at a brand name hidden in plain sight. "Sertas" is a play on "Serta," a well-known mattress company, but with an extra "s" to make it plural—so it fits "mattresses" instead of just "mattress." The word "certain" signals that you’re looking for a specific type or brand, not just any mattress. It’s a straightforward brand reference with a slight tweak for the grammar.