Bearings with a flange on the outer ring are easier to mount in a housing then standard bearings as there is much less reliance on the housing tolerance to hold the bearing securely. The flange helps to prevent the bearing from moving in an axial direction when exposed to axial loads or vibration. The flange is also an advantage when the housing fit changes due to thermal expansion. In these conditions, a flanged bearing will stay in place under an axial load. Although flanged bearings are more expensive than their non-flanged counterparts, they are very popular with designers for the above reasons.