Dual Size connector-1/4 & 5/16 – Auto-locks 1/4″ hex and 5/16″ hex bits on insertion.
Dual Size connector-5/16 & 3/8 – Auto-locks 5/16″ hex and 3/8″ hex bits on insertion.
Dual Size connector-3/8 & 7/16 – Auto-locks 3/8″ hex and 7/16″ hex bits on insertion.