The Smith sump pan receiver, used with the 1010 roof drain, is a 24-in. x 24-in. square metal plate with recessed center opening to accept the drain body flange.
This helps to eliminate puddling water around many roof drain installations thanks to the flange resting on top of a circular hole cut in the roof.
A sump receiver should be specified on all but poured-in-place roof drain installations.