Appears to be a misidentified Sigma APS-C zoom — likely the 17-50mm f/2.8 or similar, not f/1.4.
The lens cataloged as 'Sigma 17-40mm f/1.4 DC' contains a specification error — an f/1.4 aperture across 17-40mm zoom range is physically impossible with current lens technology. This record requires verification. Mount not specified.
17-40mm focal length (if accurate). f/1.4 aperture (almost certainly incorrect — verify actual spec). DC = APS-C (if accurate). Multiple mount options (if DC).
The Sigma 17-40mm f/1.4 DC does not correspond to any known Sigma product. The f/1.4 aperture is impossible for a standard zoom design. Likely a cataloging error. Closest known lenses: Sigma 17-50mm f/2.8 EX DC (id 3306), or Sigma 18-35mm f/1.8 DC HSM Art (exists but different focal range). Verify product identity from listing photos before purchase.
On the used market, verify actual lens identity — the canonical specification is almost certainly incorrect. Do not purchase without confirming the actual product.