Abstract: The hollow plug 6 is placed in the end opening of the inner tube 2 of a spirally wound package of sheet material, such as carpet. The hollow plug has a cylindrical section 10 and a conical section 11. The conical section includes approximately equal spaced elongated weakened areas or grooves 25 that spread apart in response to outwardly directed forces applied to the conical section from within the conical section. Ribs 18 extending along the outer surface of the cylindrical section tend to reduce the frictional contact between the plug and the inner tube 2 and the edge portion of the wrapping paper 4, while teeth 20 resist inadvertent withdrawal of the plug from the carpet package.