Ring Writer Clip (Set of 3) (1S 1M 1L) Tens Units Laser engraved dial face provides unmatched Ships via truck Laser engraved dial face provides unmatched accuracy * Recessed dial face and high contrast red pointer increase visability and reduce parallax errors * Lifetime calibration warranty * New 5 leg stand provides improved stability and maneuverability * Simple color changes give the aneroid a new look * Latex and mercury free * Automatic age based target zone : bpm % * To help you train safely and effectively the training computer determines your heart rate target zone limits automatically according to your age based maximum heart rate (220 minus age) 85 cm) Large 61 cm) ID * Implement is automatically positioned and angled correctly for use * Little or no gripping ability is needed * Can be used with pens pencils crayons paint brushes tooth brushes razors etc * Three sizes to fit different fingers: Small