write gap 63 is lapped together with the surrounding ceramic to form a generally spherical air bearing surface 64 to reduce the overall air bearing surface area and thus permit a closer approach of head and disk the ceramic post end is further provided with slots 65 the final component of the head is a stabilising ring 66 bonded to the post around the air bearing surface 64 further detail of the manufacture of such a head may be found in u s pat no 4 293 883 as described in the earlier referenced u s pat no 4 003 091 the function of the stabilising ring is further to stabilise the separation of the disk from the head in addition to the primary stabilisation provided by a backing plate which in the present case is constituted by the inner surface of cartridge wall 11 the ring isolates the head from the inevitable mechanical tolerance between the backing surface and the movable head assembly so that the disk is presented to the head from a very well defined reference frame attached to the head the final control of disk separation from the read write gap 63 is provided by the air.