The neck turner gives you a precise easy way to remove high spots and case neck out of roundness on the outside of the neck. The auto-feed allows you to advance the cutting tool over the case neck with each turn of the trimmer handle. This unit is only adaptable with the RCBS Case Trimmer -2. Not to be used with Trim Pro Power Case Trimmer and manual CT Trim Pro. only adaptable with the RCBS Case Trimmer -2. Not to be used with Trim Pro Power Case Trimmer and manual CT Trim Pro.Not for use with Trim Pro Powered Unit.