|image by Brian Smith|
The Keystone K 1020 SLR auto-instant Reflex was the first SLR for type no 126 film cassettes (Kodapak). It had a big selenium meter which controlled aperture. The lens and meter combination was the same as Mamiya used for its Auto-Lux 35 SLR. Maybe the Keystone camera was made by Mamiya, or the main parts of it where bought by Keystone from the Japanese company.