This Panasonic-made lens has a Leica L mount. The aperture on the lens ranges from ƒ/22 to ƒ/4.
From London Camera Exchange
Panasonic LUMIX S PRO 16-35mm F4 Lens (S-R1635E)
Camera Centre
Panasonic 16-35mm f4 Lumix S Pro L-Mount Lens
This product is also available at 3 unverified stores.