The scammer advertises in local:
Oh wow, look at this a module that will protect you from "nasty gankers" who prowl New Eden looking for targets. If you have this in your cargohold, and you can use it more than once, and when the ganker tries to fire on you this will cause you to warp to a gravimetric site that only you can access.
Clicking on the contract, which is typically an auction, you will see this:
What Happens Now
The mark will see the contract and may, if they're concerned about gankers, bid upon the item and continue to until they win.
How Can I Protect Myself
Firstly, remember Rule #1, anything posted in local in a trade hub is going to be a scam and you should not accept any contract without seriously checking on the contents and issuer.
You can confirm whether or not this magic item does what the issuer says if you look at the details for the item:
You can see, after a little patient checking that it makes no mention of the "wonders" that the contract issuer says it does about being able to escape gankers. It's not even a ship module, its used in the production of Caldari Ships.