Made of flexible nitrile rubber with temperature resistance.Includes 80 vacuum caps in six sizes: 5 pcs of 3/8 inch, 5 pcs of 5/16 inch, 10 pcs of 1/4 inch, 20 pcs of 7/32 inch, 20 pcs of 5/32 inch, and 20 pcs of 3/16 inch.Provides a tight fit to prevent vacuum leaks.Designed for use on manifolds, vacuum lines, hoses, diaphragms, and carburetors during testing.Packed in a clear plastic case measuring 20 x 11 x 3 cm for organized storage and quick size identification.Compatible with carburetor applications requiring vacuum caps sized from 5/32 inch to 3/8 inch.