Designed to measure compression rate when practicing CPR on a manikin. Worn on the students’ wrist, 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. A flexible slap-style latex free silicone rubber wristband fits any size wrist and may be used with any training manikin.