Metabones announces 'Speed Booster' lens adapter for mirrorless cameras: Digital Photography Review
Viltrox EF-Z2 Autofocus Speed Booster Adapter for Canon EF Lens to Nikon Z Camera - Supero
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
VILTROX EF-EOS M2 Lens Adapter 0.71x Speed Booster for Canon EF Lens t
Viltrox EF-R3 0.71 Speed Booster Adapter for Canon EF to Canon RF-Moun – Rent in NYC at The Imaging World Camera Rentals in Brooklyn
Metabones T Speed Booster ULTRA 0.71x Adapter for Canon EF Lens to BMPCC 4K Camera – Brazilbox
Metabones®
Speed Booster Viltrox Canon Sony | Sony Viltrox Adapter Canon | Speed Booster Ef Canon - Lens Adapter - Aliexpress