twenty one holes 0.484 in. dia, one hole 0.375 in. dia, one hole 0.344 in. dia, one hole 0.813 in. dia, one hole 0.813 in. dia, two holes 0.531 in. dia
Used on fluid cooler p/n 500-u-06024-4-6 onboard 400 & 420 wagb coast guard vessels. 6.500" outside diameter 0.125 in. wide rib located on the ctr line from the ctr to the inside wall circular