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3-1/2 in round cover, 0.119 in thick (RACO 703)

3-1/2 in round cover, 0.119 in thick (RACO 703): two #8-32 holes 2-3/4 in apart; centre knockout not modelled

Exact dimensions. True size, no printing tolerance added. Threads are plain cylinders at the major diameter.

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From the full sheet

US round and octagon ceiling boxes (3-1/2, 4 in): size, cubic inches, fixture screw spacing: every size, notes, mating features and sources. What is the fixture screw spacing of a 4 in octagon or 3-1/2 in round ceiling box?

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