What am I thinking of!!!!

Hi all, this is driving me mad. I'm thinking of a component that I'm sure exists but can't look it up as I can't remember what it is called!!!

Remember the old remote release leads for cameras when you pushed the plunger at one end and a pin came out the other releasing the shutter? It's something like that but with out the lead. Just a unit that is retracted when LOW and extended when HIGH (no smut thanks! :) ) Something like a 2 position servo but without the rotation?

Have I made this up or am I just old and forgetful? Many thanks

Solenoid?

Liniair actuator?

Solenoid!!

That's the word I was trying to remember!!!!

Many thanks! :D