A pendent residential fire prevention sprinkler has a frame structure extending from the sprinkler body, and a system for blocking an outlet to prevent fluid from passing through the outlet until occurrence of a predetermined condition and for unblocking the outlet in response to occurrence of the condition. A deflector is supported by the frame structure at a predetermined distance from the outlet, at a position to be impinged upon by the fluid leaving the outlet. The deflector has a central portion and a peripheral portion, and slots formed in the periphery, defining tines therebetween. The slots include a first plurality of slots, each of which extends inward from the deflector periphery with a uniform width, a second plurality of slots, each of which has a first portion and a second portion between the deflector periphery and the slot's closed end, where the first portion has a width that varies at different points, while the second portion has a uniform width.