Spartan lockers are lunchbox style mechanical lockers, and a lunchbox style locker is automatic lockers.
The advantage of a lunchbox style locker is, you don't have to replace the carrier. You just have to replace the spider gears. The Spartan lockers also have the same characteristics.
Spartan lockers are installed into the open differential.
When you go straight, the locker gives 100% power to both the wheels.
When you turn, the inside wheel end of the locker will unlock. When you back to move straight, it will give 100% to both the wheels again.
The alignment pins of Spartan lockers are thicker and provide enough strength.
On the downside, as the Spartan lockers are automatic lockers, sometimes they tend to show some unexpected road-handling behaviors.