Made of CV steel. Chrome-plated. With ball lock Contents: 1 adapter, 6.3 mm (1/4″) to 10 mm (3/8″) (no 2030)1 adapter, 10 mm (3/8″) to 12.5 mm (1/2″) (no 3019)1 adapter, 12.5 mm (1/2″) to 20 mm (3/4″) (no 1932)1 reducer, 10 mm (3/8″) to 6.3 mm (1/4″) (no 3020)1 reducer, 12.5 mm (1/2″) to 10 mm (3/8″) (no 1930)