HPA really is making a big comeback as more products for airsoft are coming out to utilise the compress air as power source. The latest is Wolverine Airsoft with their SMP technology... "The Wolverine Airsoft Single Moving Part (SMP) system is the next step in the evolution of HPA airsoft technology. The SMP is the first product to hit the airsoft market which departs from the model of repackaging paintball electro-pneumatic technology to fit into an airsoft gun body. By recognizing that the needs of an airsoft gun to propel a 1/4 gram bb are very different from propelling a paintball 10x that weight we were enabled to develop a design that is more efficient, less complex, safer, and cheaper.

Why the SMP?

The SMP is a drop in electro-pneumatic cylinder unit which fits into an existing gearbox. It utilizes a direct solenoid fired mechanism which reduces the number and complexity of parts. While others have experimented with direct solenoid fired designs with limited success, the key is the Wolverine Airsoft springless imbalanced poppet design. This design is currently in the process of being patented. This system has a variety of advantages:

• Engineered, manufactured, and assembled in the USA!
• One moving part (excluding the solenoid valve)
• Reduced number of critical seals
• Improved air efficiency over comparable systems
• Wide range of operating pressures (40-125psi)
• Improved cross platform compatibility
• Reduced cost due to significantly lower parts count
• True open bolt design (rear biased nozzle gives instant trigger response with no first shot dry fire)
• Safety: while sufficiently high velocities can be achieved to satisfy most every need on the airsoft field, unnecessarily high and potentially dangerous velocities are not easily attainable using an SMP system.
• The result is a total package which is more reliable, more efficient, less complex, and less expensive than any comparable product on the market. "