of the rearward dielectric insert 19 into the third adapter assembly bore portion 58 with the forward end of the insert abutting the step 60 the rearward insert bore 98 is dimensioned to receive therethrough with clearance the rearward receptacle 34 of the contact sub assembly 12 subsequently internal portions of the adapter shell indicated at 100 of fig5 are staked into the insert by suitable tooling not shown in a manner common within the industry the insert is thereby secured within the adapter shell and assembly of the adapter is thereby complete the assembled adapter assembly is illustrated by fig1 and 5 it will be appreciated that the filter sleeve 20 does not contact the internal sidewalls of the adapter assembly bore except through the annular flange of the collar this effectuates mechanical insulation of the fragile filter sleeve from externally originating stress yet does not sacrifice electrical contact since the filter sleeve is securely commoned to the adapter shell through the annular collar flange it will further be appreciated that the forward and rearward dielectric inserts 18 19 electrically insulate the forward and rearward portions 28 34 of the pin from the adapter assembly 14 referring to fig5 and 7 the instant adapter assembly 10 is intended to accommodate a contact sub assembly filter sleeve having a length variable within limits because different filtering applications require use of filters of differing lengths this capability greatly enhances the versatility of the adapter assembly fig5 illustrates a contact sub assembly 12 having a filter sleeve 20 of.