Cal-Van Tools Finger Socket Driver (Pack of 3) allows access into tight areas using 1/4 inch and 3/8 inch sockets. It has a diamond knurl design for positive grip. It includes: one (1) no.102 3/8 inch male - 1/4 inch female, one (1) no.103 1/4 inch male - 3/8 inch female, one (1) no.104 3/8 inch male - 3/8 inch female. It is patented.