We describe a second-harmonic-generation frequency-resolved optical gating measurement device optimized for the characterization of few-cycle pulses in the mid-IR spectral range. The system has a temporal range of $100\mathrm{ps}$ with resolution of $0.12\mathrm{fs}$ , and it is capable of measuring pulses as short as $1.5\text{\hspace{0.17em} cycles \hspace{0.17em}}\left(15\text{\hspace{0.17em} \hspace{0.17em}fs}\right)$ at $3\mu \mathrm{m}$ . Through interchangeable beam splitters and detectors it covers a wavelength range from $800\mathrm{nm}\text{to}5\mu \mathrm{m}$ with up to $0.5{\mathrm{cm}}^{-1}$ resolution. We demonstrate measurement of a richly featured $3.2\mu \mathrm{m}$ pulse with $9.6\text{\hspace{0.17em} cycle}$ duration, recovering the main pulse of $96\mathrm{fs}$ , as well as low-intensity post-pulses with picosecond offset. We also characterize a $100\mathrm{fs}$ pulse after dispersion through a $1\mathrm{cm}$ sapphire plate, comparing the measured phase difference with the calculated one.