i have been using a similar one from lowes in 3 different tanks for months monitored by good digital thermometers and proven - shot daily with a high end infrared laser temp gun - they work excellent - i can not tell you when i have adusted any of the three - for sure i can tell you that i have not touched them in over a month and the temp at the pad stays within 1 degree 24/7 - on the other side of my room i have 4 20 watt heat mats plugged into big apples bah 1000 and i see temp swings 5 degrees as the mats cut off and on - i know proportional is the best way to go but not everyone can afford them - looking back - except for the convenience of being able to run multiple pads off one controller and except for the cords everywhere - i would use dimmers on every tank