These Brass Wool snap caps have a spring-loaded primer plunger which prevents firing pin damage during dry-firing exercises. Treat the wool chamber mop with your favorite gun oil to prevent rusty chambers during storage. Leaving guns cocked during storage is hard on springs and is dangerous. These will help keep your shotgun in good condition.
Specifications:

Type
Caliber or Gauge	20 Gauge
Rounds Per Box	2
Material	Wool w/Metal Base
Chamber