Concrete cube mold, specifically a 150mm cast iron cube mold used for testing the compressive strength of concrete.
This type of mold is used to create standardized concrete cube samples for quality control in construction.
The mold in the image is made of cast iron and has a size of 150mm x 150mm x 150mm.
It is designed to be durable and rigid to ensure the concrete samples maintain their shape during the curing process.