Anderson Metals 5/16" Tube OD x 1/2-24 Thread Brass Compression Tube End Cap Compression Cap Ends, 300 Max psi 730081-05 - 55508543 - Penn Tool Co., Inc
Ironwerks 3/4" OD Brass Compression Cap Fitting, Stop Valve Cap, Lead-Free To Close Off Unused Pipe - 2 Pack - Amazon.com
Brass Compression Cap 3/8"
Thrifco 4401346 #61C 5/16 Inch Lead-Free Brass Compression Cap 2/Pack