A device for injection of a product into an injection site, the product being carried by a container having an open proximal end and a substantially closed distal end coupled to a needle to provide an outlet port for the product from the container , and a piston provided in the container and movable with respect to the container , the movement of the piston causing the product to be expelled from the container through the needle , said device comprising: a housing receiving at least partly said container , said container being movable relative to said housing between an initial position, in which a tip of the needle does not extend beyond a distal end of said housing , and a final position, said final position distally spaced relative to said initial position, and in which the tip of the needle extends beyond said distal end of said housing ; a needle shield releasably coupled with said container , for protecting said needle prior to use of the device ; a safety shield adapted to receive said container and located at least partially within said housing ; and a deflectable longitudinal leg which is in contact with a pushing surface of the needle shield prior to removal of said needle shield from said container , said pushing surface thereby forcing said longitudinal leg in a stressed position prior to removal of the needle shield , a distal end of the longitudinal leg being located between said pushing surface and the safety shield , said longitudinal leg deflectable from the stressed position, in which said longitudinal leg prevents said container from moving distally with respect to said housing , to a released position, in which said longitudinal leg does not prevent said container from moving distally with respect to said housing , wherein removal of said needle shield from said container causes said longitudinal leg to move from the stressed position to the released position, wherein said longitudinal leg comprises a peg , and wherein said peg engages a recess located on the safety shield when said longitudinal leg is in the stressed position and said peg disengages said recess when said longitudinal leg is in the released position. a housing receiving at least partly said container , said container being movable relative to said housing between an initial position, in which a tip of the needle does not extend beyond a distal end of said housing , and a final position, said final position distally spaced relative to said initial position, and in which the tip of the needle extends beyond said distal end of said housing ; a needle shield releasably coupled with said container , for protecting said needle prior to use of the device ; a safety shield adapted to receive said container and located at least partially within said housing ; and a deflectable longitudinal leg which is in contact with a pushing surface of the needle shield prior to removal of said needle shield from said container , said pushing surface thereby forcing said longitudinal leg in a stressed position prior to removal of the needle shield , a distal end of the longitudinal leg being located between said pushing surface and the safety shield , said longitudinal leg deflectable from the stressed position, in which said longitudinal leg prevents said container from moving distally with respect to said housing , to a released position, in which said longitudinal leg does not prevent said container from moving distally with respect to said housing , wherein removal of said needle shield from said container causes said longitudinal leg to move from the stressed position to the released position, wherein said longitudinal leg comprises a peg , and wherein said peg engages a recess located on the safety shield when said longitudinal leg is in the stressed position and said peg disengages said recess when said longitudinal leg is in the released position. <EOS>