The Emerald Clip On Aneroid Sphygmomanometer has a 2 tube system with separate bellows and gauge tubes. 

To free up one hand the Emerald features a spring loaded catch which is mounted to the rear of the dial, allowing it to be attached to the cuff or any other convenient position. 

The Emerald has a 48mm dial ensuring easy reading of pressure values and is supplied with a standard adult black nylon calibrated cuff and zip-up pouch for handy storage.