They are nice except they don't work well on the older DC or HD series dover operators. Those units require to much torque and burn up the drive boards if they are high use elevators, ok on low use as they have time to cool down. Obviously if you have a GAL operator ,its better to toss on a MOVFR, then those then those I've put them on most other elevator no issues. You do need a stop in the open direction so it can properly sense the open torque increase to set the open limit.