The Brandon lens design was invented by Chester Brandon. Don Yeier founded VERNONscope in 1958. In 1966, Don Yeier purchased the designs from Chester Brandon. Don Yeier built Brandon eyepieces and other optical accessories in Candor, NY. In 2013, Don Yeier sold the company and manufacturing moved to North Carolina. The Brandon eyepieces are now manufactured in the USA under the company name of Vernonscope LLC.
Vernonscope also makes threaded eyepieces for Questar Corporation.
You can purchase these special eyepieces from Questar.