Which of the following is an example of a re-enterable firestop material?

Firestop pillows are designed to be a re-enterable firestop material, which means they can be removed and replaced without significant damage to surrounding structures. This property is particularly useful in situations where systems or cables may need to be frequently altered or serviced. Firestop pillows are often made of intumescent materials that expand when exposed to heat, effectively sealing openings and maintaining fire resistance while allowing for future access.

In contrast, other options may not offer the same re-enterable features. For example, firestop mortar creates a permanent seal and is typically used for more structural applications where alteration is not anticipated. Composite boards and sealant tape can also be less easily removed or may not be intended for reuse in situations requiring frequent access. In applications where flexibility and maintenance need to be balanced with fire safety, re-enterable materials like firestop pillows provide the best solution.