The Halllman balls and springs are compatible with all Hallman Pro and Pro RX boost controllers. You can customize your control by changing the springs.• Fits all Hallman Pro and Pro RX Boost Controllers• (Not for the ES model)Purchase Includes:(1) Ball or Spring. Sold individually, price is for one ball or spring.More Info:The ceramic ball only weighs a fraction of what the stainless steel balls weighs. This weight difference allows the ceramic ball to act very quickly as it is constantly changing directions during operation. The ceramic ball in conjunction with the use of a lighter spring will allow very fine adjustment of boost up to 4 to 5 pounds of boost over stock in increments as low as .5 psi.Use of the ceramic ball with the heavy spring is helpful if you're only running 4-5 psi over stock and still want that fine-tune control. What's the difference between the Pro and Pro RX? Both the Pro and Pro RX share the same body. The ball and spring can be customized to suit your needs. Boost Controller PSI Ball Spring Pro High Boost(15 to 60+ PSI) 316 Stainless Steel Heavy Pro RX Low Boost(1-15 PSI) Ceramic Light See more Hallman Boost Products
