The products are made from a special heat resistant material and are designed for vacuum or manifold outlets. They fit various tube outer diameters (O.D.) and inside lengths: 1/2" O.D. with 11/16" inside length, 1/4" O.D. with 1-1/4" inside length, 1/8" O.D. with 9/16" inside length, 3/16" O.D. with 1-1/4" inside length, 3/16" O.D. with 9/16" inside length, 3/8" O.D. with 1-1/2" inside length, 3/8" O.D. with 31/32" inside length, 5/16" O.D. with 1-1/4" inside length, 5/16" O.D. with 9/16" inside length, and 1/4" O.D. with 9/16" inside length.