Type 537 and 567 BigBORE Auto-Fill Float Collars allow for automatic ﬁll from bottom while casing is being run in the hole. The valve is run in hole fully open which allows the casing to completely ﬁll. The filling action reduces casing running time and minimizes surge pressures on formations. The valve is converted to a conventional check valve by dropping a ball and pressuring up to release the upper flapper. Until the conversion ball has been dropped, the casing can be circulated at any time without affecting the fill-up operation.