Nikon FG-20 with 50mm f1.8 Nikon Series E lens mount_C Mount this viewfinder also works well

this viewfinder also works well as a viewfinder for 35mm-ish lenses on any camera

That's a Sure Shot 130 U "2"

and has had new light seals installed

The Sony A6000 is a compact interchangeable-lens mirrorless camera with a 24mp DX sensor

Nikon FG-20 with 50mm f1.8 Nikon Series E lens mount_C Mount this viewfinder also works wellThe Nikon FG 20 is a compact manual focus 35mm SLR with full manual or aperture priority autoexposure, shutter speeds from 1s to 1 1000s, and compatibility with F mount lenses from AI to AF D (in manual focus mode). In excellent condition, with accurate speeds & metering and new light seals. Includes a Nikon Series E 50mm f1. 8 lens.