This Makita Cr-Mo Impact Socket Set has 9 of the most popularly used sockets all with 1/2 inch drives and O ring mounts. Cr-Mo stands for chromium molybdenum and it is an alloy steel. It was designed for and is used extensively in the aircraft industry due to it's high tensile strength and torsional load ratings. Suited to the removal of nuts, studs etc. Contained in a hard moulded plastic carry case for storage and ease of transportation.