The following pictures give an overview of the tools that are helpful to install a Natkon dendrometer.
T-shaped dendrometer:

1: frame, 2: potentiometer, 3: rods with screws and washers (4 mm drill bit), 4: cordless screwdriver, 5: hammer, 6: screwdriver, 7: spanner #7, 8: flat nose pliers, 9: multimeter

O-shaped dendrometer:

1: dendrometer, 2: Phillips screwdriver, 3: slotted screwdriver #0, 4: chisel, 5: cutter, 6: flat nose pliers, 7: multimeter