A fluid-operated percussion drill tool comprising: an outer wear sleeve comprising a substantially cylindrical wall and having inner and outer surfaces; a percussion bit having a head portion and a bit retaining portion and located at a forward end of the outer wear sleeve; a sliding piston mounted for reciprocating movement within the outer wear sleeve to strike the percussion bit; a drive ring having a substantially cylindrical wall and comprising connection means adapted for connecting the drive ring to a drive means of the fluid-operated percussion drill tool; and characterised by an annular flange arranged around the outer wear sleeve at the forward end thereof, wherein the flange comprises a plurality of through holes provided therein and is restrained from forward movement relative to the wear sleeve by engagement of an internal shoulder provided on the flange with an external shoulder provided at the forward end of the wear sleeve; and wherein the connection means of the drive ring comprises an annular collar provided at a rear end of the drive ring, the collar comprising a plurality of holes provided in a rear end thereof, wherein each hole corresponds to one of the plurality of through holes in the flange, the collar arranged to receive the forward end of the wear sleeve such that the forward end of the wear sleeve abuts an internal shoulder of the drive ring and the rear end of the collar is arranged to abut a forward end of the flange and wherein each through hole and corresponding hole in the collar is configured to receive a fastener to connect the drive ring to the drive means of the percussion drill tool. an outer wear sleeve comprising a substantially cylindrical wall and having inner and outer surfaces; a percussion bit having a head portion and a bit retaining portion and located at a forward end of the outer wear sleeve; a sliding piston mounted for reciprocating movement within the outer wear sleeve to strike the percussion bit; a drive ring having a substantially cylindrical wall and comprising connection means adapted for connecting the drive ring to a drive means of the fluid-operated percussion drill tool; and characterised by an annular flange arranged around the outer wear sleeve at the forward end thereof, wherein the flange comprises a plurality of through holes provided therein and is restrained from forward movement relative to the wear sleeve by engagement of an internal shoulder provided on the flange with an external shoulder provided at the forward end of the wear sleeve; and wherein the connection means of the drive ring comprises an annular collar provided at a rear end of the drive ring, the collar comprising a plurality of holes provided in a rear end thereof, wherein each hole corresponds to one of the plurality of through holes in the flange, the collar arranged to receive the forward end of the wear sleeve such that the forward end of the wear sleeve abuts an internal shoulder of the drive ring and the rear end of the collar is arranged to abut a forward end of the flange and wherein each through hole and corresponding hole in the collar is configured to receive a fastener to connect the drive ring to the drive means of the percussion drill tool.