Mini/micro electronic actuators, please help!

[arcadie]

Ok im designing something and i need an actuator that will meet these needs:
- In no larger that 1.5" in diameter
- Has a liniar piston that will reach about .75-1"
- is fast enought to go from non extended to extended to 1" and back about 20 times per second.
- realy need something that will work about 500,000 times before it needs to be replaced.

im kinda new to this stuff so dont im not real sure on were to get something like this but i drew a diagram of what i need in case i wasnt clear enough in my description, here:

http://epickidz.com/actuator.bmp

 

[itsmoked]

Google for Solenoids.

 

[arcadie]

Thanks i found just what i needed!