Maintain accurate blood pressure readings & lower lifetime cost with gear-free DuraShock technology, the first major innovation in aneroid sphygmomanometer technology in nearly 100 years. By eliminating the need for gears Welch Allyn have created a more durable sphygmomanometer without the need for regular re-calibration. Part of our Gold Series, the DS66 Trigger features an innovative trigger-release design for easy operation.