They look like a cross between a motor vehicle key and a lock pick rake.
Jigglers come in a variety of styles and models, some are manufacturer dedicated. If you go that route you will need hundreds of jiggler picks for every different vehicle manufacturer. If our interested in getting into using jigglers; I would suggest a universal set (seen above) from Shomer-Tec. This set includes 10 of the most universal style of jiggler keys. I've tucked this one away inside my surreptitious entry kit.
How to use:
You will insert the jiggler into the key hole and use a "jiggling" action. Basically a shaky-up/down-in/out type motion. While slightly turning as you would with a normal key to open the vehicle. You may have to go through multiple try-out keys to you find the right one (hence why they call them try-out keys).
I feel this is another good skill set to have. Just like lockpicking, this will help you acquire needed resources in a grid down situation.
Check out Shomer-Tec for this set.