Sigma's budget standard zoom — the basic AF-E 28-70mm for unknown mount.
The Sigma AF-E 28-70mm f/3.5-4.5 is a basic standard zoom from Sigma's budget range. The AF-E designation suggests an early AF design. The 28-70mm covers the basic standard range. Variable aperture. Mount not specified — verify before purchase. A basic Sigma zoom at minimum specification with no distinguishing features.
Basic Sigma quality at the entry level. Variable aperture. The 28-70mm is the minimum standard zoom range. Sharpness acceptable stopped down. No distinguishing features. Better Sigma standard zooms exist at every mount at similar near-zero pricing. Not a lens to seek out for any purpose. Verify mount before purchase.
Mount not specified — the AF-E designation doesn't clearly identify the mount. Verify carefully. Weight varies. Build quality basic. The variable aperture and basic specification provide no advantage over better alternatives available at similar near-zero pricing in the declining used lens market.
Essentially valueless. Verify mount. Basic quality with no distinguishing features. Better alternatives free in every mount. Not recommended for purchase when better options cost the same. Only if bundled free with a camera body in the correct mount.