2-part, unique, steel-filled epoxy repair compound that is fast to mix and apply. Once hardened, it can be machined, drilled, tapped or filed.LOCTITE PC 3965 (known as LOCTITE FIXMASTER FAST SET STEEL EPOXY) is a metallic gray, 2-part, unique, steel-filled epoxy repair compound that is fast to mix and apply. Once hardened, it can be machined, drilled, tapped or filed. It's excellent for fast, cost effective repairs to all ferrous materials. It is typically used in applications with an operating range of -20 °F to +200 °F (-30 °C to +95 °C).