Designed to measure compression rate and depth when practicing CPR on a manikin. Worn on the students’ wrist, the CRdM will provide an audible “beep” when compression depth is not within the range of 5-6cm (2”-2.3”). A diode illuminates red when compressions are below 100 cpm or above 120 cpm. When compression rate is between 100 and 120 cpm the diode illuminates green, allowing users to self-check their timing.