$$\require{cancel}$$
As already noted this maximum torque is experienced when the magnet is at right angles to the magnetic field. In SI units, "unit magnetic field" means, of course, one tesla, and the SI units of magnetic moment are $$\text{N m T}^{−1}$$ , or newton metres per tesla. The reader should look up (or deduce) the dimension of magnetic field (teslas) and then show that the dimensions of magnetic moment are $$\text{L}^{2} \text{T}^{−1} \text{Q}$$.