Seven-manifolds of G 2 holonomy provide a bridge between M-theory and string theory, via Kaluza-Klein reduction to Calabi-Yau six-manifolds. We find first-order equations for a new family of G 2 metrics D 7 , with S 3 × S 3 principal orbits. These are related at weak string coupling to the resolved conifold, paralleling earlier examples B 7 that are related to the deformed conifold, allowing a deeper study of topology change and mirror symmetry in M-theory. The D 7 metrics' non-trivial parameter characterises the squashing of an S 3 bolt, which limits to S 2 at weak coupling. In general the D 7 metrics are asymptotically locally conical, with a nowhere-singular circle action.