E 20mm f/2.8 Lens from Sony, a super compact "pancake" lens designed for APS-C-format E-mount cameras where it provides a 30mm equivalent focal length.
With its pancake design, the lens only extends 0.8" from the mount, resulting in a compact and lightweight camera system.
Bright f/2.8 maximum aperture suits working in available lighting and also contributes to the sleek size and lightweight design.