Carlon 1-Gang 18 cu. in. PVC Round Old Work Electrical Box B618RR - The Home Depot
Sigma Engineered Solutions, White Sigma Electric 143854WH 1/2-Inch 5 Hole Round Box - Electrical Outlet Boxes - Amazon.com
4 in. Round Weatherproof Electrical Junction Box Cover with 1/2 in. NPT Thread Outlet for Indoor/Outdoor Use – Landscape Accessories – Bronze - Amazon.com
Electrical product information - ROUND JUNCTION BOX WHITE : ElectricSmarts Network
Lorex ACCJ7R3B Outdoor Round Junction Box for 3-Screw ACCJ7R3B
Sigma Engineered Solutions Metal Weatherproof New Work Round Electrical Box in the Electrical Boxes department at Lowes.com