This is a bag of DuraFix Skimming Coat, which is a water-based ready-mixed acrylic compound. It’s used for a variety of purposes such as filling wall cracks, creating a smooth surface on masonry walls, and as a finish coat over plaster. It's good for both interior and exterior use and has several benefits like being easy to sand and paint, providing a smooth finish, and not requiring a primer. It’s also fast-drying and non-asbestos. The application instructions suggest applying it with a trowel, plaster knife, or spray, and it seems to have an expiration date which is visible, indicating when it should be used by for best results.