A device for mixing bone cement material, the device comprising a mixing body having a chamber, and wherein the mixing body has an open end； a lid arranged to be fitted to the open end； means for mixing bone cement material in the chamber, the means for mixing comprising a rod extending through the lid and into the chamber, wherein the rod has a frangible portion； said lid comprising a cap moveable to a first position covering the frangible portion of the rod, and to a second position revealing the frangible portion. The device also has a plunger at the other end of the mixing body which can be set in position to control the volume of the mixing chamber during mixing.
