A retort clamp cross pattern aluminium extension is a piece of laboratory equipment used in the process of distillation. It is made of aluminium and is designed to secure a retort, which is a type of flask used for distillation, to a ring stand. The cross pattern provides stability and support for the retort, and the aluminium material offers durability and resistance to corrosion.

The extension component allows for additional height to be added to the setup as needed. This type of retort clamp is commonly used in chemistry and chemical engineering experiments, as well as in other applications that require the distillation of liquids.