Everything You Wanted to Know About Speed Boosters but Were Afraid to Ask | B&H eXplora
Metabones Speed Booster VS $20 Adapter - YouTube
GEAR REVIEW: The Metabones Speed Booster for that Full-Frame Look Pt1
Official announcement - Metabones Speed Booster ULTRA - EOSHD.com - Filmmaking Gear and Camera Reviews
Metabones Speed Booster adapter gives lenses an extra f/stop and nearly full frame focal lengths on APS-C sensors - Newsshooter
EDIT: Now with new "Bokeh Circles" tests....An adaptor which claims to make your lens, faster, wider and better! This is NOT an April Fool's! | Philip Bloom- Blog