Comparison between NGC 4337 mean α-element ratios (black solid square) including error bars derived from Table 5, with data from old open clusters in the inner disc from Magrini et al. (2010; blue triangles) and inner disc giants from Bensby et al. (2010; grey dots). The black solid circle indicates Trumpler 20 from Carraro et al. (2014b), and the red circles are NGC 4815 and NGC 6705 from Magrini et al. (2014).