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