Abstract: An injection apparatus can include a hand-held unit having a head portion and a body portion. The head portion can include a base member, a needle fluidly coupled to the base member, a movable portion disposed over the needle and being axially movable relative to the base member between an extended position and a retracted position in which a distal point of the needle is exposed, a safety cover removably coupled to the base member, the safety cover comprising one or more extension members, and an adjustment member removably coupled to the movable portion and configured to adjust a penetration depth of the needle by increasing or decreasing a distance between the movable portion and the base member.