Check the listing for details. BlackHeart Premium Crossbow Rail Lube. Condition: New. Listed at 11.63 USD. BlackHeart Premium Crossbow Rail Lube [BHA10103] A lubricated rail is a fast rail - BlackHeart's premium rail lube creates a slippery surface for your string to glide across. In short, it vastly improves shot consistency and extends the life of your string - it's legit. Reduces Center-Serving WearIdeal Viscosity for applicationScent-Free FormulaIncreased Velocity .5 oz. bottle Mfg Number: 10103 WARNING: This product may contain chemicals known to the State of California to cause cancer and birth defects or other reproductive harm. For more information, go to www.P65Warnings.ca.gov.WARNING: This product may contain chemicals known to the State of California to cause cancer and birth defects or other reproductive harm. For more information, go to www.P65Warnings.ca.gov.WARNING: This product may contain chemicals known to the State of California to cause cancer and birth defects or other reproductive harm. For more information, go to www.P65Warnings.ca.gov.