A device for mixing bone cement material, the device comprising: a mixing body having a chamber, and wherein the mixing body has a first end and a second end; a lid arranged to be fitted to the first 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 first end and a second end, wherein a paddle portion is provided at said second end of the rod; means for dispensing bone cement material from said mixing body attached to a second end of the mixing body, wherein the means for dispensing the bone cement material is a plunger movable by the application of force through the chamber, said plunger provided to set an adjustable volume in the chamber prior to mixing; said device further comprising: means for positioning the plunger between the first and the second end of the mixing body to define a volume of the chamber; and means for maintaining the position of the plunger so as to maintain the volume of the chamber during mixing; and characterized in that the lid comprises: an inner cap and an outer cap fitted over the inner cap, and wherein the outer cap is movable relative to the inner cap such that, when the outer cap is moved away from the inner cap to the first position, the outer cap covers a frangible portion; and wherein, when the outer cap is moved to the second portion to fit over the inner cap, the frangible portion of the rod is revealed, and wherein the outer cap has a protrusion that extends through the chamber to engage with the paddle portion when the outer cap is in the second position. a mixing body having a chamber, and wherein the mixing body has a first end and a second end; a lid arranged to be fitted to the first 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 first end and a second end, wherein a paddle portion is provided at said second end of the rod; means for dispensing bone cement material from said mixing body attached to a second end of the mixing body, wherein the means for dispensing the bone cement material is a plunger movable by the application of force through the chamber, said plunger provided to set an adjustable volume in the chamber prior to mixing; said device further comprising: means for positioning the plunger between the first and the second end of the mixing body to define a volume of the chamber; and means for maintaining the position of the plunger so as to maintain the volume of the chamber during mixing; and characterized in that the lid comprises: an inner cap and an outer cap fitted over the inner cap, and wherein the outer cap is movable relative to the inner cap such that, when the outer cap is moved away from the inner cap to the first position, the outer cap covers a frangible portion; and wherein, when the outer cap is moved to the second portion to fit over the inner cap, the frangible portion of the rod is revealed, and wherein the outer cap has a protrusion that extends through the chamber to engage with the paddle portion when the outer cap is in the second position. means for positioning the plunger between the first and the second end of the mixing body to define a volume of the chamber; and means for maintaining the position of the plunger so as to maintain the volume of the chamber during mixing; and characterized in that the lid comprises: an inner cap and an outer cap fitted over the inner cap, and wherein the outer cap is movable relative to the inner cap such that, when the outer cap is moved away from the inner cap to the first position, the outer cap covers a frangible portion; and wherein, when the outer cap is moved to the second portion to fit over the inner cap, the frangible portion of the rod is revealed, and wherein the outer cap has a protrusion that extends through the chamber to engage with the paddle portion when the outer cap is in the second position.