A needle unit (20) comprising: a needle hub (21) comprising a needle (23) and a needle shield (22), wherein the needle hub (21) and the needle shield (22) are arranged to form a needle unit (20) where the needle hub is arranged displaceably inside the needle shield such that the needle hub is displaceable along an axis which is parallel with the longitudinal axis of the needle (23) between a shielded position and an exposed position. The needle hub (21) further comprises a first hub locking element (24) and a second hub locking element (26) and the needle shield (22) further comprises a first shield locking element (25) and a second shield locking element (27), said first hub locking element (24) and said first shield locking element (25) engaging each other in the shielded position to establish a first releasable locking mechanism (24, 25) between the needle hub (21) and the needle shield (22), said second hub locking element (26) and said second shield locking element (27) engaging each other in the shielded position to establish a second locking mechanism (26, 27) between the needle hub (21) and the needle shield (22), both the first and second locking mechanisms (24, 25, 26, 27) being arranged as shock proof locks, and where the first releasable lock mechanism (24, 25) is arranged to engage with the lock release element (31) of the injection device (1) when the needle unit (20) is coupled to the injection device, said engagement allowing the first releasable lock mechanism (24, 25) to be unlocked. The invention further provides an injection device comprising the needle unit and a method of assembling an injection device with the needle unit.La présente invention concerne un bloc aiguille (20) comprenant : un raccord (21) d'aiguille comprenant une aiguille (23) et un protecteur (22) d'aiguille, le raccord (21) d'aiguille et le protecteur (22) d'aiguille étant agencés de manière à former un bloc aiguille (20), ledit raccord d'aiguille étant agencé de manière à êtr
