1. Introduction

2. Sample selection and observations
2.1. Radcliffe/SAAO spectra
2.2. FEROS/ESO spectra
2.3. VISTA Variables in Via Lactea survey
2.4. Other photometric data

3. Results
3.1. Spectro-photometric characterization
3.2. Distance estimation
3.4. A possible massive white dwarf near the ZZ Ceti instability strip
3.5. Kinematics

4. Summary and conclusions