Crosstac Crown Saver 5.56 / 223 5/8-24 threads Black. Precision CNC machined from solid delrin caliber sized and precisely threaded to fit. Crown Savers align the brush/rod junction over the crown preventing accuracy reducing damage to the all-important muzzle crown. In addition the slick delrin allows you to easily feel when to reverse the brush and prevent reversing the brush while partially inside the bore. Helps capture the spray from the brush when it exits the bore (crown savers are the diameter of the cleaning brush). Available in popular calibers - select the one for your rifle threads and bore. Specifications for Crosstac Crown Savers: Manufacturer: Crosstac Fabric/Material: Delrin Plastic Quantity: 1 Package Contents: Crosstac Crown Savers Crosstac 135725-223T: Crown Saver 5.56 / 223 5/8-24 threads Black