Oval vacuum cups come in two styles.
Oval concave (OC) vacuum cups are like universal cups except the cup is elongated to provide a larger surface area and thus a stronger grip.
Oval flat (OF) vacuum cups have bottom cleats to maintain a larger area exposed to vacuum. Because of this, the cleats reduce the stroke by almost half. They should only be used on flat or very slightly curved surfaces.
Oval vacuum cups can seal to cylindrical object but only along the cup long axis (be mindful of minimum radius).
Whenever possible, use several round vacuum cups instead of oval vacuum cups as round vacuum cups are more forgiving of mounting misalignment and workpiece deflection.