3006~7 3PCS 1/4″DR. Extension Bar: 2 “, 4”, 6 “. 3606~10 4PCS 3/8″DR. Extension Bar: 1-3/4 “, 3”, 6 “, 10”. 3613~16 4PCS 1/2″DR. Extension Bar: 2 “, 3”, 5 “, 10”.