A safety needle device, comprising: a housing configured to couple to a syringe, the housing having a proximal end, a distal end, and a housing body; a needle hub disposed on the proximal end of the housing; a needle cannula attached to the needle hub, the needle cannula having a length; an activation latch disposed on an outer surface of the housing body; a retractable sheath on an inner surface of the housing body, the retractable sheath having a proximal end and a distal end, a retention shelf disposed on the proximal end of the retractable sheath; a lockout latch disposed on retractable sheath to cover a distal tip of the needle cannula; and a spring element disposed in the housing body and attached to the distal end of the retractable sheath characterized in that: the retention shelf releasably engaged to the activation latch in an initial state by engagement of the activation latch with the retention shelf until the activation latch is depressed, wherein when in the initial state the distal tip of the needle cannula is partially exposed; the proximal end of the retractable sheath moves between an initial position in the initial state, a retracted position and an extended position with respect to the housing, wherein the initial position partially exposes the distal tip of the needle cannula, the retracted position fully exposes the needle cannula and the extended position fully covers the distal tip of the needle cannula; wherein the needle cannula is injected to a desired depth by utilizing the full length of the needle cannula or a significantly shorter distance of the needle cannula. a housing configured to couple to a syringe, the housing having a proximal end, a distal end, and a housing body; a needle hub disposed on the proximal end of the housing; a needle cannula attached to the needle hub, the needle cannula having a length; an activation latch disposed on an outer surface of the housing body; a retractable sheath on an inner surface of the housing body, the retractable sheath having a proximal end and a distal end, a retention shelf disposed on the proximal end of the retractable sheath; a lockout latch disposed on retractable sheath to cover a distal tip of the needle cannula; and a spring element disposed in the housing body and attached to the distal end of the retractable sheath characterized in that: the retention shelf releasably engaged to the activation latch in an initial state by engagement of the activation latch with the retention shelf until the activation latch is depressed, wherein when in the initial state the distal tip of the needle cannula is partially exposed; the proximal end of the retractable sheath moves between an initial position in the initial state, a retracted position and an extended position with respect to the housing, wherein the initial position partially exposes the distal tip of the needle cannula, the retracted position fully exposes the needle cannula and the extended position fully covers the distal tip of the needle cannula; wherein the needle cannula is injected to a desired depth by utilizing the full length of the needle cannula or a significantly shorter distance of the needle cannula. the retention shelf releasably engaged to the activation latch in an initial state by engagement of the activation latch with the retention shelf until the activation latch is depressed, wherein when in the initial state the distal tip of the needle cannula is partially exposed; the proximal end of the retractable sheath moves between an initial position in the initial state, a retracted position and an extended position with respect to the housing, wherein the initial position partially exposes the distal tip of the needle cannula, the retracted position fully exposes the needle cannula and the extended position fully covers the distal tip of the needle cannula; wherein the needle cannula is injected to a desired depth by utilizing the full length of the needle cannula or a significantly shorter distance of the needle cannula.