6.5″ dia. Full Backer Casting for all Direct Tank Fill Flanges 500153 Part No. 500153 Use this backer casting with all direct tank fill flanges. Gasket 500139 available. Part Number 500141 Split Backer Plates also available for use inside existing water tanks when adding a direct tank fill flange to an existing water tank. Description 6.5" dia. backer casting for use with 3" all Direct Tank Fill Flanges. Download Part Drawing Material Stainless Steel Dimensions 3" Weight (approx.) 2.4 lbs.