The Contain-its are snug fitting plastic discs used to keep epoxy from drooling out of the socket, and the inspector off your back when setting dowel bars. The disc also protects the installer from epoxy that splatters back  when entrapped air pockets burst as the bar is pressed into the socket. Contain-Its are available for bar sizes 4 to 12 (1/2″ to 1 1/2″).