Wrenches with a double head or end, such as the Teng Tools 19mm x 22mm Metric Double Head/End Open Flare Nut Wrench and Teng 621213 Double Open Ended Spanner, offer versatility and convenience.

Crow's-foot 3/8-inch drive open end sockets. These are sort of like an open-end wrench but have never proved to be all that handy. Good for situations where one can only go straight on a bolt or nut.

A reader says this is the smallest open-end wrench in the world, with 0.005 in. across the flats on one end and 0.010 in. across the other. The human hair next to the wrench gives a comparative size.