Hubbell Raco 4 in. Octagon Box, Drawn, 1-1/2 in. Deep, Two 1/2 & Six 3/4 in. KO's, Raised Ground, Gray, (126): Electrical Boxes: Amazon.com: Tools & Home Improvement
RACO 1-Gang Metal New Work Octagonal Electrical Box in the Electrical Boxes department at Lowes.com