Airsoftjunkiez got in stock the Bullgear CNC Hop-Up for Tokyo Marui MP7 Series that use the (Bingo/PolarStar/Jack HPA Engine)... "This isn't just a replacement CNC hop up for Bullgear CNC Hop-Up for Tokyo Marui MP7 Series (Bingo / PolarStar / Jack HPA Engine). Made out of full metal so it will last longer and give you the edge in accuracy. Do make sure you use the original hop up and inner barrel. Once the barrel is connected to the chamber itself, there is absolutely no wobble at all which increases it's reliability. Modern hop up chambers uses a spinning dial to adjust the hop which is far more reliable than previous versions and will account for more precise adjustments. It will only allow you to use the Bingo/PolarStar/Jack HPA Engine for all HPA lovers out there. "