Well, I though this should be pretty straight-forward, but apparently not. I ended up buying these:

https://www.ebay.com/p/2pcs-Universa...d=323635719483

....with the thinking that when you energize the wires wires one way, the plunger extends and then flip the polarity and the plunger retracts. Well, that's not what happens. Basically, the plunger starts out in a "neutral" position, and when you energize the wires one way, the plunger extends and as soon as you disconnect power, it returns to the neutral position. Flip the polarity and the plunger retracts and as soon as you disconnect power, returns to neutral. Obviously this is not what I want. I want to apply power in one direction that will extend the plunger and the plunger remains extended when power is removed.....then flip polarity and the plunger would retract and remain retracted when power is removed. Anyone know of a source for something like this besides going with a "linear actuator" that costs $40 each and has 150 pounds of force?