They are made of Black Acetal Plastic. This is the Classic version of the side release with good performance and rugged looks. This version is still favoured by many including the British military and has been proven over many years. Side release buckles come in many forms and styles to suit exacting standards and offer many structural and aesthetic features. A centre support rib for crush resistance, a reduction in overall length of the buckle and a design which allows the beauty of your product to show through are just a few features of our plastic buckles. Acetal does not absorb moisture and so is better suited to marine and other applications where it may be in prolonged contact with fluids.