The new Z-System is Tokyo Marui's latest entry into the GBB rifle market featuring an action similar to the venerable Hi-Capa design as opposed to standard gas M4 systems.
The Z-System has been designed to not only be much more gas efficient, but it has been designed with durability and longevity in mind thanks in part to its short travel roller style hammer; this hammer design greatly reduces the cyclic wear on your bolt, hammer, and valve knocker.
Additional improvements include a steel bolt locking plate which addresses a common issue with standard gas M4 systems where the bolt stop suffers from accelerated wear and quickly loses the last round bolt locking function.