A horizontal sidewall sprinkler (1, 100, 600, 900) comprising: a sprinkler body (2,100, 610, 910) having an inlet passage (3, 101, 601, 901) for supply of a fluid and an outlet, the outlet being closed by a sealing assembly prior to actuation of the sprinkler; a sleeve body (9, 190, 615, 915) secured to the sprinkler body; a yoke (7, 195, 660, 960) substantially spanning a width of the sleeve body, the yoke urging a load screw (15, 160, 685, 985) against a surface of the sealing assembly facing an occupancy, and being held in place prior to actuation of the sprinkler by two levers (4, 130, 670, 970) that are joined by a soldered link (6, 150, 680, 980); a slide plate (10,220, 635, 935) located near an inner wall of the sprinkler body facing the occupancy prior to actuation of the sprinkler, the slide plate having a central aperture for fitting over the inlet passage; a frame (710, 1010) or two guide pins (14, 230) for bearing and supporting a deflector (17, 320, 750, 1050), wherein the deflector is positioned between the load screw and the sealing assembly thereby obstructing a flow of fluid from the outlet upon actuation of the sprinkler; and a spring (11, 170, 620, 920) provided in the sprinkler body, between the inner wall of the sprinkler body and pressing the slide plate and the frame or the two guide pins away from the inner wall, wherein upon actuation of the sprinkler, the levers, the yoke and the load screw are forced out of and away from the sprinkler by the force of the fluid, the spring forces the slide plate outward from the inner wall, and the force of the fluid moves the deflector away from the slide plate to a position for delivery of the fluid to the protected area. a sprinkler body (2,100, 610, 910) having an inlet passage (3, 101, 601, 901) for supply of a fluid and an outlet, the outlet being closed by a sealing assembly prior to actuation of the sprinkler; a sleeve body (9, 190, 615, 915) secured to the sprinkler body; a yoke (7, 195, 660, 960) substantially spanning a width of the sleeve body, the yoke urging a load screw (15, 160, 685, 985) against a surface of the sealing assembly facing an occupancy, and being held in place prior to actuation of the sprinkler by two levers (4, 130, 670, 970) that are joined by a soldered link (6, 150, 680, 980); a slide plate (10,220, 635, 935) located near an inner wall of the sprinkler body facing the occupancy prior to actuation of the sprinkler, the slide plate having a central aperture for fitting over the inlet passage; a frame (710, 1010) or two guide pins (14, 230) for bearing and supporting a deflector (17, 320, 750, 1050), wherein the deflector is positioned between the load screw and the sealing assembly thereby obstructing a flow of fluid from the outlet upon actuation of the sprinkler; and a spring (11, 170, 620, 920) provided in the sprinkler body, between the inner wall of the sprinkler body and pressing the slide plate and the frame or the two guide pins away from the inner wall, wherein upon actuation of the sprinkler, the levers, the yoke and the load screw are forced out of and away from the sprinkler by the force of the fluid, the spring forces the slide plate outward from the inner wall, and the force of the fluid moves the deflector away from the slide plate to a position for delivery of the fluid to the protected area.