A pen needle assembly, comprising: a hub (12) adapted to receive a medication pen body having a compartment therein； a needle cannula (14) attached to the hub (12) having a distal end extending from the distal end of the hub (12) and a proximal end adapted to access the medication compartment in the pen body； a first passive shield (44) with a distal end at or proximal to the distal end of the hub (12) during injection arranged in the hub (12) and surrounding the needle cannula (14)； an elastic loading member (98) that loads the first passive shield (44) to a distal position that covers the needle cannula (14) after injection； an outer sleeve (18) attached to the hub (12) having a distal end surrounding the first passive shield (44) and hub (12)； an outer shield (42) radially outward of the first passive shield (44) and radially inward of said outer sleeve (18), said outer shield (42) covering the needle cannula (14) in an initial state before use； characterized in that the proximal movement of the outer shield (42) followed by its rotation releases the first passive shield (44), such that the first passive shield (44) moves distally under the thrust of the elastic loading member (98 ) to cover the needle cannula (14) in position after use； and wherein the distal end of the hub (12) extends beyond the distal end of the outer sleeve (18), and the distance between the distal tip of the needle (14) and the distal end of the hub (12) is depth effective penetration of the needle (14).Un conjunto de aguja de pluma, que comprende: un cubo (12) adaptado para recibir un cuerpo de pluma de medicación que tiene un compartimento en el mismo； una cánula de aguja (14) fijada al cubo (12) teniendo un extremo distal que se extiende desde el extremo distal del cubo (12) y un extremo proximal adaptado para acceder al compartimento de medicación en el cuerpo de pluma； un primer escudo pasivo (44) con un extremo distal en o proximal respecto al extremo distal del cubo (12) durante la i
