Which type of firestop is pliable and moldable for fitting into openings?

The option that describes a firestop that is pliable and moldable for fitting into openings is the non-mechanical firestop. This type of firestop material is typically made from substances such as a fire-resistant caulk or foam, which allows it to be easily shaped and contoured to fill irregular spaces around electrical or data cables, pipes, and other penetrations in fire-rated walls or floors. The adaptability of non-mechanical firestops is crucial for achieving a tight seal that can effectively prevent the passage of fire, smoke, and gases, adhering well to various substrates and ensuring compliance with fire safety standards.

Non-mechanical firestops are particularly advantageous in complex installations where rigid materials might not easily conform to openings or may not provide the flexibility required for effective sealing. This characteristic is important in allowing for movement and expansion of building materials without compromising the firestop's integrity.