Device and mixing and/or reconstitution method

A device comprising:

• a housing;
• a first chamber within the housing, wherein the first chamber contains a first material;
• a second chamber containing a first piston and a second piston, wherein the first piston and the second piston are axially moveable within the second chamber;
• and
• a second material initially contained within the second chamber between the first piston and the second piston,
• wherein the device is adapted such that activation of the device causes movement of one of the first piston or the second piston in an axial direction of the device thereby
• moving the other of the first piston and the second piston in the axial direction of the device,
• opening a fluid communication path between the second chamber and the first chamber, and
• expelling the second material from the second chamber into the first chamber via the fluid communication path, and
• wherein the device further comprises a plunger which closes a proximal end of the first chamber within the housing, wherein the plunger contains the second chamber, wherein the plunger is axially moveable within the housing of the device, and wherein axial movement of the plunger within the housing activates the device and causes a pressure drop in the first chamber;
• and wherein the plunger comprises a through-hole at its distal end closed by a plug, which is connected with the second piston.