Soft rubber boot to safely grip the spark plug during removal and installation. 3/8" Drive and 9/16" size. One piece design prevents damage due to wobble. Knurled handle prevents slipping from hand. 3/8" drive for use with ratchet and breaker bars. Specialty spark plug socket for 2004-current Ford F-150 pickup trucks with 5.4L 3-valve Triton V-8 engines. 3/8" Drive with 9/16" Socket end. Extension is part of the socket. Easily fits down spark plug tube in cylinder head.