It depends on what you need it for, but your best bet will likely be a linear actuator with a DC or AC control system. We have some you can take a look at, if you click the link below. It's hard to say without knowing what you want to use it for.
It's probably best to find out the parameters of your project before going much further.
Matt
ActuatorZone
It's probably best to find out the parameters of your project before going much further.
Matt
ActuatorZone