US Patent 7458613 Rotatable fire sprinkler fitting

A fire sprinkler fitting has a cylindrical body and an insert. The insert has an inner end which is disposed within a proximal portion of the bore, such that the outer end protrudes beyond the open bore end by a distance D. The outer end has internal threads which are sized and dimensioned to accept and retain a fire sprinkler therein. The insert is rotatable within the body without effecting the distance D.