Everything you love about the Spire III with upgraded performance and improved reliability. New Proactive feeding logic that works more reliably. Virtue iFI wireless integration with compatible markers. Upgraded cosmetics. Toolless electronics for easy N-Charge battery pack installation. Spire IV Proactive Logic The Spire IV features all new proactive feeding logic. Unlike previous Spire models, which required constant sensor readings from every shot (with the potential for adding in extra unnecessary spins while shooting, and could potentially result in slow rates of fire from a sensor malfunction), the Spire IV features the new Proactive Logic. Now your Spire IV starts feeding the instant the first shot is fired, and continues to feed automatically, without relying on continuous sensor readings until the stack is full. This is the same proven technology incorporated into the CTRL loader, which works more consistently and reliably on every type of marker. Spire IV iFI Wireless Technology The Spire IV has been upgraded to work with the Virtue Ace wireless iFI platform. This new feeding technology allows for a tight integration between the loader and the marker and also maintains backwards compatibility on guns without iFI technology using the new Proactive Feeding logic pioneered on the CTRL loader. When the Spire IV is paired with the Virtue Ace or iFI compatible boards, the loader maintains instant communication with the marker's eyes which allows for significant improvements as both the gun and the loader are now synced together for faster and more consistent feeding, stopping and idle performance. And if the gun's eyes are turned off, dirty or if the Spire IV is used on a different gun, the Spire IV automatically transitions to the new proactive feeding mode, which will automatically feed with every shot until the stack is full.