This is a Panasonic-made lens that has a 0.25 magnification ratio. The lens has a maximum ƒ/4 aperture and a minimum ƒ/22.
From Photospecialist
Panasonic Lumix G LEICA DG VARIO-ELMAR 100-400mm F/4.0-6.3 II ASPH. POWER OIS
OnBuy
Panasonic Leica DG Vario-Elmar 100-400mm F/4-6.3 II ASPH. POWER O.I.S. Lens (H-RSA100400)