A gauge hanger 10 and a setting tool 12 are disclosed. The setting tool 12 includes an electro-mechanical impact driver 26 and a drive shaft 28 which extends out of an outer casing 12. The gauge hanger 10 comprises a nut 32 which can be engaged by the drive shaft 28. When the nut 32 is rotated it can draw a threaded mandrel 36 upwardly in a wellbore. This causes the grippers 40 in a linkage assembly to be driven radially outwardly so that they can grip the sides of the wellbore. A pin 52 is designed to shear once the grippers have engaged with the sides of the wellbore so that the setting tool 12 can be lifted clear.