(B28mounting)(4H) 4 Hole Mount is typically used on flexible material that is not strong enough to support the movement from the center (CMT) . (CMT) Center Mount used for mounting to translucent or thin materials. (FA) Front Access used for mounting the clock movement into a solid wall where access is not available from the rear (RA). (RA) Rear Access used for mounting the clock movement into a solid wall from the rear. (SM) Surface Mount used when the movement cannot be recess into the wall.