Abstract: An apparatus for injecting a substance into a human or animal comprising a body, a needle coupled to the body and terminating in a point and a needle guard mounted on the body for movement from a retracted position in which the guard does not shield the needle to an extended position in which the guard shields the needle. The needle guard can be releasably retained in the retracted position and locked in the extended position. Locking of the needle guard is accomplished by interlocking members carried by the needle guard and by a collar mounted on the body.

Abstract: An apparatus for injecting a substance into a human or animal comprising a body adapted to have the substance to be injected pass therethrough, a needle mounted on the body and a needle guard mounted on the body between an extended position in which the guard obstructs access to the point of the needle and a retracted position in which the guard does not materially obstruct access to the point of the needle. The guard is releasably retained in the retracted position, and interlocking members on the body and the guard are responsive to generally axial movement of the guard to the extended position for interlocking to substantially prevent movement of the guard back toward the retracted position.