The items in the image are plastic concrete cube moulds used for testing the compressive strength of concrete. Purpose: Designed to shape concrete specimens into standard cubes for laboratory testing. Material: Made from durable, lightweight, and reusable plastic, making them corrosion-resistant. Dimensions: Commonly available in sizes such as \(150\text{mm}\times 150\text{mm}\times 150\text{mm}\) or \(100\text{mm}\) variants.