There is some ambiguity in the use of NGC 2174 and NGC 2175 identifiers. The following information will clarify this issue:

NGC 2174 is an H II emission nebula (Sh2-252) located in the constellation Orion. The prominent HII region Sh2-252 was originally catalogued by Sharpless (1959), who related it to an emission nebula (NGC 2174) and a loose stellar distribution (NGC 2175). Currently, NGC 2174 refers to the whole HII region, while NGC 2175 refers to a possible young open cluster (OC) or a stellar group of scattered stars in the nebula.

(Bonatto, C.; Bica, E., 2011).

Latest investigations reveals existence of the six young clusters associated with that large, diffuse H II region NGC 2174. Their designations are Sh2-252A, Sh2-252C, Sh2-252E, NGC2175s, Teutsch 136 and one possible young open cluster or stellar group NGC2175. The distance from the Sun to this single star-forming complex is 1.4 kpc or 4566 ly (Bonatto & Bica 2011). All these clusters have an estimated age of 5 Myr or less, consistent with the age of the primary ionizing source, the O6.5 V star HD 42088 (Garnier & Lortet-Zuckermann 1971; Felli et al. 1977; Jose et al. 2012).