"OD 21 INS, ID 9.187 INS, THICKNESS OF FLANGE IS 1 IN. PLUS 0.250 IN. SPIGOT, O/A LG STUDS INCLUDED 10.250 INS, CONSISTS OF 2 HALVES AND PACKING GLAND, FLANGE HAS 10 EA 0.938 IN. DIA DRILLED HOLES ON 18.875 IN. DIA BETWEEN CENTERS FOR MOUNTING TO BULKHEAD"