The utility model discloses an adopt allen key who can be used to narrow space, the overcoat is equipped with including six arris plug and handles, be provided with radial hole in six arris plug main parts, or the matching cover outside six arris plugs, is provided with radial hole on the overcoat, both can not the rotation restraining structure to be provided with the messenger between six arris plugs and the overcoat, the handle matches to be installed in radial hole and ability endwise slip. The utility model discloses with the handle along radially insert rotatory main part in, can compress the axial height of six interior arris spanners to make in it is applicable to narrow space, improve its stability in use moreover. The handle meets when nearly the obstacle position can not be rotated, only needs inwards to push in the radial hole rotation operations once more with the handle, and it is very convenient to operate, obviously improves work efficiency.