portion 36 of the sleeve member 13 is defined exteriorly by an axially outwardly narrowing frusto conical fourth cam surface 47 arranged to be engaged by the second cam surface 29 30 of the nut member 12 to constrict the mid portion of the sleeve member 13 radially inwardly to the made up arrangement of the fitting as shown in fig5 the axially outer portion 37 of the sleeve member 13 includes a radially inner cylindrical surface 48 having a diameter slightly greater than the outside diameter of the tube end 14 the axially outer end of the sleeve member is further defined by a radial surface 49 at the inner end of the cylindrical surface 48 and defining at the junction therewith a sharp annular biting edge 50 arranged to bite into the tube 14 in the made up arrangement of the fitting as shown in fig5 the outer portion 37 of the sleeve member 13 is defined exteriorly by a frusto conically axially outwardly narrowing fifth cam surface 51 which comprises an extension of the cam surface 47 the radial constriction of the end portion 37 of the sleeve member 13 effected by engagement of the nut member cam surfaces 29 and 30 with the cam surface 51 of the sleeve member effects a radial constriction of the outer portion 37 to cause the surface 48 therewith to be in intimate facial engagement with the tube wall in the made up arrangement of the fitting and the sharp edge 50 to be pressed into the outer surface of the tube wall in such arrangement in one specific illustrative embodiment of the.