Abstract: A ratchet wrench for adjustment of scaffolding screw jacks. The wrench includes a head member having an asymmetrical passage of fixed dimension adapted to receive the scaffolding leg. Dog members or flippers are positioned adjacent the passage in the head and are retained for perpendicular pivotal rotation with respect to the head. Each flipper includes an engaging surface and a sloped relief surface. Gravity induces the downward rotation of the flippers permitting the driving engagement of the jack in a first direction while contact between the screw jack and sloped flipper relief surface urges the flipper upwardly facilitating the non-driving wrench return stroke. The flippers are symmetrically designed thereby facilitating the selective raising or lowering of the screw jack simply by positioning the wrench with the appropriate head surface facing upwardly.