Boyle's Law Apparatus-EIS-PH0142GL offers a thoughtfully designed, durable resource for hands-on learning. Mounted on durable metal base Total height 8.3" Manometer dual scale is from 0-4 x 105Pa and 0-58 PSI with needle set at atmospheric pressure Requires 1.5 v AA battery for operation The Eisco Labs Boyle's Law Apparatus can be used to demonstrate the relationship between pressure and volume of gas. The unit consists of a 1.14" (29mm) dia. graduated cylinder with a piston and a screw valve. Cylinder acts upon a manometer through a narrow passage of 2.3" (60mm) dia. Manometer dual scale is from 0–4 x 105 Pa and 0–58 PSI with needle set at atmospheric pressure.