Product Overview This refreshed product summary organizes the verified details available for Hallman Replacement Ball / Spring.Available Details What's the difference between the Pro and Pro RX? Catalog detail: Ball Verified detail: 316 Stainless Steel Product detail: (1-15 PSI) Boost Controller: PSI / Ball / Spring Verified detail: Purchase Includes Part Number: HBC-BALL-STEEL 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.. Verified detail: Boost Controller Product detail: High Boost Catalog detail: Pro RX Verified detail: Light Pro Rx: Low Boost (1-15 PSI) / Ceramic / Light Part Number: HBC-BALL-CERAMIC Pro: High Boost (15 to 60+ PSI) / 316 Stainless Steel / Heavy 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.