A plumbing fitting, comprising: a housing (7, 47) having at least one receiving member, said at least one receiving member defining a cylindrical bore for receiving a piping member therein; at least one annular seal fittingly inserted in an annular groove formed in said receiving member, said at least one annular seal dimensioned to sealingly engage with said piping member; an annular locking member comprising an annular base and teeth (6, 7) extending inwardly for locking said piping member within said receiving member, said annular locking member dimensioned for receiving said piping member therethrough; wherein the plumbing fitting further comprises a receiving element inserted in said receiving member, said annular base being dimensioned for contacting the receiving element, the receiving element comprising at least one nipple adapted to be inserted into a matching slot (160, 161) of the receiving member; and an annular releasing member inserted within said receiving element and said receiving member comprising a beveled portion and at least one nipple dimensioned to enter into a slot of the receiving element, said annular releasing member being dimensioned to receive said piping member therethrough, and said annular releasing member being movable within said receiving element between a locking position for locking said pipe into said receiving member whereat said beveled portion abuts against a shoulder formed in an inner surface of said receiving element, and a releasing position whereat said beveled portion presses against said teeth (6, 7) of said annular locking member for releasing said piping member. a housing (7, 47) having at least one receiving member, said at least one receiving member defining a cylindrical bore for receiving a piping member therein; at least one annular seal fittingly inserted in an annular groove formed in said receiving member, said at least one annular seal dimensioned to sealingly engage with said piping member; an annular locking member comprising an annular base and teeth (6, 7) extending inwardly for locking said piping member within said receiving member, said annular locking member dimensioned for receiving said piping member therethrough; wherein the plumbing fitting further comprises a receiving element inserted in said receiving member, said annular base being dimensioned for contacting the receiving element, the receiving element comprising at least one nipple adapted to be inserted into a matching slot (160, 161) of the receiving member; and an annular releasing member inserted within said receiving element and said receiving member comprising a beveled portion and at least one nipple dimensioned to enter into a slot of the receiving element, said annular releasing member being dimensioned to receive said piping member therethrough, and said annular releasing member being movable within said receiving element between a locking position for locking said pipe into said receiving member whereat said beveled portion abuts against a shoulder formed in an inner surface of said receiving element, and a releasing position whereat said beveled portion presses against said teeth (6, 7) of said annular locking member for releasing said piping member.