This Viewfinder Eyecup from SmallRig features a soft, silicone design to ensure comfort, reduce eye fatigue, and keep sunlight from entering your viewfinder. It's compatible with the eyepiece of the Sony a7 IV, a7S III, a7R V, a1, a1 II, and a9 III mirrorless cameras.
It easily attaches to the viewfinder using a snap-on design and doesn't block any display or ports. It can also provide added protection to the camera from scratches and knocks.