Now you can control headspace. The Redding Competition Shellholder Kit #1 consists of five shellholders in varying heights with increments of .002". Allows you to increase or decrease the case to chamber headspace without adjusting the dies. Storage box included. Each shellholder has a distinct black oxide finish and is clearly marked to indicate the amount it will decrease case-to-chamber headspace. You can now easily adjust the shoulder bump to customize cases to your specific chamber. Technical Information:Packaged 5 piece set in .002" increments (+.002", +.004", +.008" and +.010") Each shellholder is clearly marked to indicate the amount it will decrease case to chamber headspace. Set allows you to adjust case to chamber headspace of your reloads with a simple shellholder change..