Amazon.com: (Pack of 8) 1-5/8" - 1-625 Inch OD Head Dia - (10-14 Ga - 1.36" - 1.45" ID) Snap-in Round Black Plastic Plugs w/Flexible Ridges | Fencing Post Tube Inserts
Pipe Caps - MOCAP Plastic Pipe Caps
Formufit 1 in. Furniture Grade PVC External Flat End Cap in White (10-Pack) F001EEC-WH-10 - The Home Depot
Plastic Supply PVCCA10 PVC Plain End Cap, 10" Dia, 10-3/4" Socket ID: Industrial Hvac Components: Amazon.com: Tools & Home Improvement