An irrigation sprinkler comprising: a base defining an axis; a pressurized water inlet mounted onto said base; a nozzle, communicating with said inlet, and providing a pressurized water stream which is generally outwardly directed relative to said axis, said nozzle being selectable to provide a selectable water stream quantity which may be less than, equal to or greater than a predetermined water stream quantity; and a water stream deflector rotatable about said axis for intermittently engaging said pressurized water stream from said nozzle and deflecting at least part of said water stream generally azimuthally with respect to said axis, said water stream deflector comprising a first pressurized water stream engagement surface and a second pressurized water stream engagement surface downstream of said first pressurized water stream engagement surface; characterized in that said first pressurized water stream engagement surface has a pressurized water stream directing configuration including at least one vane, which divides said pressurized water stream into a first portion of said pressurized water stream and at least a second portion (1104, 1106) of said pressurized water stream, arranged to direct said first portion of said pressurized water stream impinging on said first pressurized water stream engagement surface, which does not exceed said predetermined water stream quantity, onto said second pressurized water stream engagement surface, and to direct said at least a second portion (1104, 1106) of said pressurized water stream impinging on said first pressurized water stream engagement surface, which at least a second portion exceeds said predetermined water stream quantity, not onto said second pressurized water stream engagement surface. a base defining an axis; a pressurized water inlet mounted onto said base; a nozzle, communicating with said inlet, and providing a pressurized water stream which is generally outwardly directed relative to said axis, said nozzle being selectable to provide a selectable water stream quantity which may be less than, equal to or greater than a predetermined water stream quantity; and a water stream deflector rotatable about said axis for intermittently engaging said pressurized water stream from said nozzle and deflecting at least part of said water stream generally azimuthally with respect to said axis, said water stream deflector comprising a first pressurized water stream engagement surface and a second pressurized water stream engagement surface downstream of said first pressurized water stream engagement surface; characterized in that said first pressurized water stream engagement surface has a pressurized water stream directing configuration including at least one vane, which divides said pressurized water stream into a first portion of said pressurized water stream and at least a second portion (1104, 1106) of said pressurized water stream, arranged to direct said first portion of said pressurized water stream impinging on said first pressurized water stream engagement surface, which does not exceed said predetermined water stream quantity, onto said second pressurized water stream engagement surface, and to direct said at least a second portion (1104, 1106) of said pressurized water stream impinging on said first pressurized water stream engagement surface, which at least a second portion exceeds said predetermined water stream quantity, not onto said second pressurized water stream engagement surface.