Reducing Union Compression NFS Product Specification Part No. Tube Size 1 Tube Size 2 21045 1/4 1/8 21046 1/4 3/16 21047 5/16 1/4 21048 3/8 1/4 21049 3/8 5/16 21050 1/2 3/8 21051 5/8 3/8 21052 5/8 1/2