SAE 4-Bolt Standard Adapters – with O-Ring Groove SAE Code 61 Flange Pad with through holes and O-Ring groove are designed to accommodate both UNC and metric hardware. Swivel feature permits angular alignment of mating flange and/or valve, improving power unit quality and aesthetics. Step-size models, the uncommon 3 ½” size, and Stainless Steel versions are available for rapid delivery.