The larger of the two adjustable AN wrenches, extending the useful range up into the bigger hose end and adapter sizes where a small adjustable simply will not open far enough. Large fittings are where damage happens most easily: they need real torque to seat, and a conventional adjustable slipping on a big anodised nut will mark it permanently. The AN-profile jaws take hold of the flats properly so you can apply that torque cleanly. Sensible for anyone building large-bore oil, fuel or intercooler plumbing. As always, hold the mating adapter with a second spanner so the tightening load is not fed into the hose.