Can these be used with an impact wrench?

Absolutely! In fact, I can't imagine using these extractors without one. One caveat: they fit a 3/8" drive, and impact wrenches are typically 1/2" drives. No worries, though. Just use a 3/8"-to-1/2" adapter to connect a given sized bolt-grip to a 1/2" extension bar connected to a 1/2" impact wrench, and hammer away! The Bolt-Grip extractors are hardened. I removed a dozen rust-welded 14mm nuts that were original to a 16yo exhaust using this tool--and they didnt have a mark on them afterwards. Just an amazing product!