A full auto registered sear is a highly versatile and valuable investment. A registered sear can be moved from host gun to host gun (legally). This allows you have fully automatic fire on the host gun. There are transferable H&K sears for sale that can be installed on various platforms. You can also find drop In auto sears for the AR15 platform, which can turn an AR15 into a machine gun. In the industry and on listing sites, you will see sellers abbreviate drop in auto sear as D.I.A.S. (DIAS). The registered sears are often times more expensive than a full gun because of their ability to be installed on different hosts.