Smail (Slow Motion Actuator with Integrated Logic) features same size & mounting as the TORTOISE (sold separately). Compatible with all DCC systems that provide accessory address control. Two-wire connection to DCC bus with no external power necessary. Easy programming. May also be controlled with panel switches or detection circuits. Adjustable throw speed. Power up position user definable or will default to last used. Other specifications same as TORTOISE (#800-6000).