May contribute to the transparency and refractive index of the lens. Heteromer composed of three CRYAA and one CRYAB subunits. Aggregates with homologous proteins, including the small heat shock protein HSPB1, to form large heteromeric complexes. Inter-subunit bridging via zinc ions enhances stability, which is crucial as there is no protein turn over in the lens. Lens as well as other tissues. Belongs to the small heat shock protein (HSP20) family.