Used to measure the temperature variance to determine the effect on setting time of fresh concrete. The right column marker indicates maximum temperature and left column marker indicates minimum temperature. Markers remain in position until reset. LA-0545 has a push button reset. K-0545 has magnetic reset and is made from heavy-weight plastic. Both units include dual scale ranges of -40 °F to 120 °F and -40 °C to 50 °C.