For instructions on how to measure for a replacement drain ring, visit our resource page, How to Measure a Roof Drain Ring.
This ring is 3 bolt and has flats on two sides. It is also a flat bottom ring.
O.D. : 14-1/4"-in. [13"-in. O.D. on the flats and gravel stop]
Bolt-to Adjacent Bolt: 7-3/4"-in.