All Kreg drivers feature a solid 1-piece construction, magnetic tip and Kreg Quick-Change chuck compatibility for fast and easy bit changes. This combo includes one 3 in (76 mm) square driver and one 6 in (152 mm) square driver. The 6 in version offers the most flexibility and ease-of use for your projects. The 3 in version is handy when you are working in tight spots where the 6 in driver can't reach.