A replacement for the Arrow Retention Spring, this innovative, high quality nylon-filament Arrow Retention Brush improves arrow grip and alignment while reducing noise and vibration. The standard scope mount (dovetail) must have six (6) holes in the top, and the extended dovetail must have seven (7) holes in the top to be able to mount the arrow retention brush. If not, the HCA-078 (standard) or HCA-079 (extended) dovetail must be purchased. Older crossbows with the RangeMaster Cam (adjustable dovetail) cannot be retrofitted with the Arrow Retention Brush.