This widely used and low cost apparatus is ideal for gathering data in support of Boyle's Law. It is supplied with a cap to seal the calibrated syringe and a packet of lubricant. A series of uniform masses (such as textbooks) are added to the top platform and the corresponding volume is read on the way down and again on the way back up to give useful average values. Students then plot pressure versus the reciprocal of the volume in search of a straight line.