Jolting Jacks are a variation of the Crawler Zombies (also known as Nova Crawlers) that appear in Alpha Omega, featured in Call of Duty: Black Ops 4. The Crawler Zombies themselves are a mutation of Zombies.
Jolting Jacks are skinny grey zombies that run on all fours, just like their regular counterpart. The feature that sets them apart is that they are surrounded by electricity and can shoot electric bolts from a distance. They usually sit on rooftops and shoot from above, but occasionally come down. The Jolting Jacks do not have a specific round, and instead spawn in with the regular zombies after the Pack-a-Punch machine is activated.
When killed, they will explode with a burst of electricity, similar to the rest of their variants. This burst does not deal damage to the player, however.