An attachable needle assembly for use on a medication delivery pen, the needle assembly comprising: a housing enclosing: a hub being fixed to a communication needle, the hub being configured to engage the medication delivery pen and the communication needle being configured to pierce a reservoir septum of the medication delivery pen; a communication septum (172, 176) of the needle assembly defining a septum chamber, the septum chamber of the needle assembly being in continuous fluid communication with the communication needle; a plurality of needles disposed in the communication septum (172, 176) of the needle assembly; wherein when the housing is in a first position, the plurality of needles is not exposed, each of a proximal end of the plurality of needles is disposed in the communication septum (172, 176) and each of a distal end of the plurality of needles is disposed in a sealing septum, and when the housing is in a second position, the selected needle of the plurality of needles is in fluid communication with the septum chamber of the communication septum (172, 176) of the needle assembly and exposed for medicament delivery and a proximal end of each of a remaining plurality of needles is disposed in the communication septum (172, 176); characterized in that the attachable needle assembly further comprises: a follower ring that automatically rotates and identifies which needle of the plurality of needles is to be selected, the follower ring including an opening; and a snap ring that applies a force to expose the selected needle and move the selected needle to be in fluid communication with the septum chamber of the communication septum (172, 176) of the needle assembly, the snap ring including a flange that mates with the opening; and the follower ring and the snap ring rotate with respect to the housing and move axially with the housing when the housing travels between the first position and the second position. a housing enclosing: a hub being fixed to a communication needle, the hub being configured to engage the medication delivery pen and the communication needle being configured to pierce a reservoir septum of the medication delivery pen; a communication septum (172, 176) of the needle assembly defining a septum chamber, the septum chamber of the needle assembly being in continuous fluid communication with the communication needle; a plurality of needles disposed in the communication septum (172, 176) of the needle assembly; wherein a hub being fixed to a communication needle, the hub being configured to engage the medication delivery pen and the communication needle being configured to pierce a reservoir septum of the medication delivery pen; a communication septum (172, 176) of the needle assembly defining a septum chamber, the septum chamber of the needle assembly being in continuous fluid communication with the communication needle; a plurality of needles disposed in the communication septum (172, 176) of the needle assembly; wherein when the housing is in a first position, the plurality of needles is not exposed, each of a proximal end of the plurality of needles is disposed in the communication septum (172, 176) and each of a distal end of the plurality of needles is disposed in a sealing septum, and when the housing is in a second position, the selected needle of the plurality of needles is in fluid communication with the septum chamber of the communication septum (172, 176) of the needle assembly and exposed for medicament delivery and a proximal end of each of a remaining plurality of needles is disposed in the communication septum (172, 176); characterized in that the attachable needle assembly further comprises: a follower ring that automatically rotates and identifies which needle of the plurality of needles is to be selected, the follower ring including an opening; and a snap ring that applies a force to expose the selected needle and move the selected needle to be in fluid communication with the septum chamber of the communication septum (172, 176) of the needle assembly, the snap ring including a flange that mates with the opening; and a follower ring that automatically rotates and identifies which needle of the plurality of needles is to be selected, the follower ring including an opening; and a snap ring that applies a force to expose the selected needle and move the selected needle to be in fluid communication with the septum chamber of the communication septum (172, 176) of the needle assembly, the snap ring including a flange that mates with the opening; and the follower ring and the snap ring rotate with respect to the housing and move axially with the housing when the housing travels between the first position and the second position.